Central-line associated bloodstream infections in intensive care units before and after implementation of daily antiseptic bathing with chlorhexidine or octenidine - A post-hoc analysis of a cluster-randomised controlled trial

doi:10.21203/rs.3.rs-1644513/v1

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Research Article

Central-line associated bloodstream infections in intensive care units before and after implementation of daily antiseptic bathing with chlorhexidine or octenidine - A post-hoc analysis of a cluster-randomised controlled trial

https://doi.org/10.21203/rs.3.rs-1644513/v1

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published 03 Jun, 2023

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Backgrounds: Antiseptic bathing did not reduce central-line (CL) associated bloodstream infection (CLABSI) rates in intensive care units (ICU) according to a recent cluster randomised controlled trial (cRCT). However, this analysis did not consider baseline infection rates. Our post-hoc analysis of this cRCT aimed to use a before-after comparison to examine the effect of daily bathing with chlorhexidine, octenidine or water and soap (control) on ICU-attributable CLABSI rates.

Methods: A post-hoc analysis of a multi-center cRCT was done. ICUs that did not yet perform routine antiseptic bathing were randomly assigned to one of three study groups applying daily bathing with 2% chlorhexidine-impregnated cloths, 0.08% octenidine wash mitts or water and soap (control) for 12 months. Baseline data was assessed 12 months before the intervention started when all ICUs routinely used water and soap. Poisson regression and generalised estimating equation (GEE) models were applied to identify changes of CLABSI rates per 1000 CL days between intervention and baseline periods in each study group.

Results: The cRCT was conducted in 72 ICUs (24 per study group) including 76,139 patients in baseline and 76,815 patients in intervention period. In the chlorhexidine group, incidence density of CLABSI was reduced from 1.48 to 0.90 CLABSI per 1000 CL days comparing baseline versus intervention period (p = 0.0085). No reduction was observed in the octenidine group (1.26 versus 1.47 CLABSI per 1000 CL days, p = 0.8735) and the control group (1.20 versus 1.17, p = 0.3298). Adjusted incidence rate ratios (intervention versus baseline) were 0.63 (95%CI 0.46 – 0.87, p=0.0172) in the chlorhexidine, 1.17 (95%CI 0.79 – 1.72, p=0.5111) in the octenidine and 0.98 (95%CI 0.60 – 1.58, p=0.9190) in the control group. The preventive effect of chlorhexidine was particularly found in ICUs with ≥0.8 CLABSI per 1000 CL days at baseline.

Conclusions: This post hoc before-after analysis of a cluster-randomised decolonisation trial suggests that especially ICUs with CLABSI rates ≥0.8 but not < 0.8 CLABSI per 1000 CL might benefit from application of 2% chlorhexidine-impregnated cloths. Antiseptic bathing with 0.08% octenidine wash mitts did not reduce ICU-attributable CLABSI.

Trial registration: Registration number DRKS00010475, registration date August 18, 2016

CLABSI

antiseptic bathing

chlorhexidine gluconate

octenidine dihydrochloride

post-hoc before-after analysis

Pathogens on the body surface of patients are considered a relevant reservoir of nosocomial infections including central-line associated bloodstream infections (CLABSI) (1). Prevention of CLABSI is crucial, as these healthcare-associated infections (HAI) are associated with increased morbidity, mortality and costs especially in intensive care patients (2, 3). Decolonisation strategies aim to reduce the number of bacteria on the skin of patients, and subsequently may prevent infections (4).

Several meta-analyses and large-scale randomised controlled trials demonstrate that daily antiseptic bathing with chlorhexidine can significantly reduce bloodstream infections (BSI) and CLABSI in ICUs (5–12). However, there is still uncertainty whether effectiveness of chlorhexidine-impregnated cloths on CLABSI rates is restricted to ICUs with high infection rates at baseline or certain types of ICUs. Clinical studies that did not show a preventive effect of chlorhexidine-impregnated cloths started with very low rates at baseline or were conducted in non-medical, but surgical ICUs (13, 14).

We conducted the CLIP-ID (Climate and pathogens – impact of decolonisation) study, a cluster-randomised controlled trial (cRCT) in 72 adult intensive care units (ICUs) in Germany and Austria. In the a priori analysis of our cRCT we found no significant preventive effect of 2% chlorhexidine-impregnated cloths or 0.08% octenidine wash mitts on CLABSI rates in ICUs compared to routine care with water and soap (control) (15). However, our results showed consistent tendencies for the effects of chlorhexidine (risk ratios below 1) and octenidine (risk ratios above 1) on CLABSI rates. Our main analysis had a high likelihood of being underpowered as CLABSI rates were 40% lower than initially expected for our sample size calculation. Adding a pre-test (before period) usually increases the power and precision of statistical tests. Further, a before-after analysis allows considering baseline infection rates and other potential ICU-specific differences between the study groups that might have an impact on CLABSI rates. Thus, in this study, we conducted a post-hoc before-after analysis of our cRCT.

In addition to chlorhexidine-impregnated cloths, we also investigated octenidine wash mitts in our trial, because Octenidine dihydrochloride represents a cost-efficient, widely used, easily available antiseptic substance in several European countries (16, 17). Clinical trials on the effect of antiseptic bathing with octenidine are scarce (18, 19).

Our post-hoc study aimed to analyse the effect of three daily bathing regimes for intensive care patients (2% chlorhexidine-impregnated cloths, 0.08% octenidine wash mitts or continuation of routine care with water and soap as control) on CLABSI rates in a before-after comparison.

Trial design and participants

We performed a post-hoc before-after analysis of the CLIP-ID (climate and pathogens – impact of decolonisation) study. Information on trial design and participants can be found elsewhere (15). Briefly, we conducted a cluster-randomised controlled trial (cRCT) on 72 ICUs in 68 German and Austrian hospitals. Each ICU that represented one cluster was randomly assigned to one of three study groups. Participating ICUs were required to fulfil the following prerequisites: i) Continuous surveillance of CLABSI in ICU-KISS during baseline and intervention period, ii) Medical, surgical or interdisciplinary ICUs, iii) CLABSI rates above the median of the respective ICU-KISS reference data within 18 months before recruitment (January 1, 2014 – June 30, 2015) or voluntary ICUs with interest in the study and iv) routine bathing regime without antiseptic substances before the intervention period started.

The post-hoc before-after analysis consisted of a 12-months baseline (water and soap) period and a 12-months so called “intervention period” (chlorhexidine or octenidine or water and soap). The baseline period lasted from February 1, 2016 to January 31, 2017 and the intervention period from February 1, 2017 to January 31, 2018 in the octenidine and control group. In the chlorhexidine group, baseline (June 1, 2016 to May 31, 2017) and intervention period (June 1, 2017 to May 31, 2018) started four months later due to difficulties in the supply chain.

Interventions

Each ICU was randomly assigned to one of three bathing regimes: daily patient bathing with non-antiseptic soap and water (control, routine care), daily bathing with 2% chlorhexidine-impregnated cloths (Sage 2% Chlorhexidine Gluconate (CHG)) or 0.08% octenidine disposable wash mitts (Octenisan® by Schülke). Chlorhexidine gluconate is a cationic biguanide compound with strong activity against gram-positive and weaker activity against gram-negative bacteria (20). Long-term routine use of chlorhexidine may enhance the development of non-susceptibility to this antiseptic substance (21–25). Octenidine dihydrochloride is a cationic byspiridine that shows activity against gram-positive and gram-negative bacteria (19, 20). Superiority of octenidine has been demonstrated in vitro in its antiseptic efficacy compared to chlorhexidine (21). To date, no resistances have been described for octenidine (16, 22).

All ICUs received standard operating protocols (SOP), and education material on infection control and daily bathing procedures (printed material and short videos on step-by-step instructions for bathing and frequently asked questions (FAQs) as downloads) according to their group allocation. Posters and information leaflets were provided to inform patients, patient’s legal representatives, and visitors on participation of the ICU in the trial. All ICUs were encouraged to perform patient bathing at least once a day by trained nurses, to continue all medical interventions including catheter care according to their hygiene plans and standard operating protocols. In the intervention groups, antiseptic products were applied according to manufacturer’s instructions, one (if necessary, more) package(s) of antiseptic products was recommended per patient and day, and on-site trainings were provided by employees of Stryker for chlorhexidine-impregnated cloths and by employees of Schülke for octenidine-impregnated wash mitts.

Details on interventions can be found elsewhere (15). Briefly, in the routine care group, bathing was continued with any non-antiseptic soap (and water). In the chlorhexidine group, 2% chlorhexidine-impregnated cloths were used below, and non-chlorhexidine containing disposable cloths (provided by Sage Products / Stryker) above the jaw line. Skin care and prophylactic products not provided for treatment were obliged to be compatible with chlorhexidine or dispensed; superficial wounds and devices were allowed to be cleansed by chlorhexidine-impregnated cloths. In the octenidine group, skin care or prophylactic products were allowed to be continued without any restrictions, the face and superficial wounds were allowed to be cleansed by octenidine wash mitts. It was not trained to clean devices with octenidine wash mitts. Compliance monitoring for bathing procedures was done by charting packages of antiseptic products consumed per month and ward and random on-site visits by study personnel in each study group.

Treating physicians and the ICU personnel were responsible for local quality management including on-site implementation of routine care and interventions as well as the management of adverse events. ICUs identified at least two individuals (hygiene and/or ICU team) in charge for conducting the CLIP-ID trial on their ward. Adverse events and consumption of decolonisation products were reported monthly to the CLIP-ID study management team. All ICUs were obliged to provide feedback and participate in surveys on infection prevention measures of their wards before and at the end of the intervention period.

The full study protocol including all documentation forms and surveys can be found elsewhere (15).

Outcomes

This post-hoc before-after analysis of the CLIP-ID cRCT is based on data provided by ICU-KISS, the German national surveillance system for nosocomial infections. Trained nurses and doctors conduced unit-based surveillance by collecting unit-based, anonymous data on number of patients, patient days, days with medical devices (e.g. mechanical ventilation, CL), and HAI including CLABSI. All definitions and details on unit-based surveillance in ICU-KISS can be found in the ICU-KISS protocol (26).

This analysis was done for the primary outcome CLABSI associated with the stay on a participating ICU standardized by central line (CL)-days. Briefly, the definition of CL association to qualify a CLABSI required the following: CL being present at onset of infection (first day with symptoms) or one day before onset of infection for at least the third day. The association to a participating ICU required acquisition of CLABSI on the third day post admission to the ICU at the earliest, while the day of admission was counted as day 1. Further criteria must be met as described elsewhere (15) and in the ICU-KISS protocol (26):

Detection of one or more pathogen(s) in one or more blood samples taken for the purpose of diagnosis or treatment by culture-based or non-culture-based methods and the pathogen identified must not be associated to an infection at another site or
Detection of the same skin bacterium in at least two separate blood samples taken for the purpose of diagnosis or treatment by cultural or non-cultural methods and the pathogen identified must not be associated to an infection on another site and at least one of the following signs or symptoms occurred: fever (> 38°C), chills, hypotension.

The number of CLABSI with any pathogen was aggregated by the number of CLABSI with gram-positive, gram-negative bacteria, and CLABSI with other causes (fungi or other than fungi, gram-positive or gram-negative pathogens).

Further subgroups analysed were CLABSI with gram-positive bacteria, coagulase-negative staphylococci (CoNS) and gram-negative bacteria.

Sample size

For this post-hoc before-after analysis, no sample size calculation was performed.

Randomisation and masking

Details on randomisation and masking can be found elsewhere (15).

Statistical analysis

All analyses were done with aggregated data on ICU-level. Incidence density of CLABSI was defined as number of newly acquired CLABSI per 1,000 CL days. For all incidence rates, exact Poisson 95% confidence intervals (95%CI) were calculated. In the descriptive analysis, numbers with percentages, pooled means and / or medians with interquartile ranges (IQR) were calculated. P-values were calculated by Chi-square, Mid P exact, Wilcoxon rank sum, Kruskal Wallis or McNemar test.

Differences of incidence densities were tested by unadjusted Poisson regression models. For each outcome, the trial effect was measured by crude incidence rate ratios (IRR) that calculated whether the incidence densities of CLABSI differed significantly between intervention and baseline periods in each study group (chlorhexidine, octenidine and control group). Baseline period included 12 months before the intervention was started for the two intervention groups applying chlorhexidine or octendidine, and the respective first 12 months for the control group continuing daily patient bathing with water and soap.

Crude incidence rate ratios were stratified by high or low CLABSI rates at baseline defined by ≥ or < 0.8 CLABSI per 1000 CL-days that represents the median of all ICUs at baseline.

In the multivariable analysis, we applied generalised estimating equation (GEE) models based on monthly ward-level aggregated data with negative binomial distribution and accounting for clustering effects (27). We used three generalised estimating equation (GEE) models to compare the outcomes CLABSI with any pathogen, CLABSI with gram-positive bacteria, CLABSI with CoNS and CLABSI with gram-negative bacteria of each study group between the intervention and the baseline period. The GEE offset variable was the logarithmised number of CL days. Ward-level parameters including mechanical ventilation and patients’ length of stay in the current month were determined as possible confounders and considered in all models. The pooled mean for length of stay was defined as number of patient days of ICUs divided by the number of ICU patients, while the pooled mean of mechanical ventilation rate was calculated as number of ventilation days of ICUs divided by the number of patient days of ICUs (multiplied by 100). All parameters added one degree of freedom to the model.

For CLABSI with any pathogen, GEE models were stratified by ICUs with low incidence density of CLABSI at baseline (< 0.8 CLABSI per 1000 CL days) and ICUs with high incidence density of CLABSI at baseline (≥ 0.8 CLABSI per 1000 CL days).

P-values less than 0.05 were considered significant. All analyses were performed using SPSS 25 (IBM SPSS statistics, Somer, NY, USA) and SAS 9.3 (SAS Institute, Cary, NC, USA).

Sensitivity analysis

We did sensitivity analyses to account for potential confounders. Additional confounders for sensitivity analysis included medical ICU (yes / no), antibiotic-coated central lines (yes / no), chlorhexidine-impregnated central-line dressings (yes / no) and needleless devices (yes / no) during the intervention period. Medical ICU was counted as “yes” for all ICUs assigned as medical ICUs, all other ICUs (surgical, medical-surgical) were counted as “no”. This data was assessed by ICU-KISS basic data or surveys conducted before and at the end of the intervention period.

Our post-hoc analysis included 76,139 patients in the baseline and 76,815 patients in the intervention period (Fig. 1 and Table 1). The cRCT was conducted in 72 ICUs (24 ICUs per study group). An overview of our before-after trial design is shown in Fig. 1.

Table 1

Characteristics of the study population (ICUs), outcomes and crude incidence rate ratios of intervention versus baseline periods, according to the study group.
Parameter	Description	Study group
		Chlorhexidine		Octenidine		Routine care (control arm)
		Baseline	Intervention	Baseline	Intervention	Baseline	Intervention
ICUs	N	24	24	24	24	24	24
Patients	N	21,346	22,897	26,095	25,127	28,698	28,791
Patient days	N	75,593	85,135	92,597	90,820	98,726	103,356
CL days	N	46,011	54,305	60,430	58,656	66,670	70,068
Length of stay [days]^b	Pooled mean	3.5	3.6	3.7	3.4	3.5	3.6
	Median (IQR), p-value^a	3.7 (2.6–4.6)	3.6 (2.7–4.2), 0.9179^a	3.6 (2.7–4.5)	3.6 (2.7–4.5), 1.000^a	3.3 (2.9–4.2)	3.3 (2.9–4.6), 0.7880^a
CL use [%]^b	Pooled mean	60.9	64.6	63.8	67.53	65.3	67.8
	Median (IQR), p-value^a	63.4 (55.6–77.5)	67.9 (55.8–77.6), 0.8366^a	68.4 (45.3–78.5)	64.9 (43.7–77.5), 0.8528^a	68.5 (60.0-76.8)	65.3 (58.6–79.1), 0.8200^a
Mechanical ventilation [%]^b	Pooled mean	34.4	30.8	37.7	35.5	31.9	36.9
	Median (IQR), p-value^a	33.2 (24.6–45.9)	33.1 (26.7–47.4), 0.8206^a	28.2 (17.9–41.3)	30.1 (16.6–39.5), 0.9671 ^a	32.2 (24.4–44.9)	34.5 (24.6–48.1), 0.8850^a
Outcomes
CLABSI with any pathogen	N	68	49	76	86	80	82
	ID / 1000 CL days (95%CI)	1.48 (1.15–1.87)	0.90 (0.67–1.19)	1.26 (0.99–1.57)	1.47 (1.17–1.81)	1.20 (0.95–1.49)	1.17 (0.93–1.45)
Compared to baseline in each study group	IRR (95%CI), p-value	1 = reference	0.61 (0.42–0.88), 0.0085	1 = reference	1.17 (0.86–1.59), 0.3298	1 = reference	0.98 (0.72–1.33), 0.8735
CLABSI with gram-positive bacteria	N	45	28	51	72	52	55
	ID / 1000 CL days (95%CI)	0.98 (0.71–1.31)	0.52 (0.34–0.75)	0.84 (0.63–1.11)	1.23 (0.96–1.55)	0.78 (0.58–1.02)	0.79 (0.59–1.02)
Compared to baseline in each study group	IRR (95%CI), p-value	1 = reference	0.53 (0.33–0.85), 0.0078*	1 = reference	1.45 (1.02–2.08), 0.0407*	1 = reference	1.01 (0.69–1.47), 0.9737
CLABSI with CoNS	N	25	11	31	43	25	26
	ID / 1000 CL days (95%CI)	0.54 (0.35–0.80)	0.20 (0.10–0.36)	0.51 (0.35–0.73)	0.73 (0.53–0.98)	0.38 (0.24–0.55)	0.37 (0.24–0.564)
Compared to baseline in each study group	IRR (95%CI), p-value	1 = reference	0.37 (0.18–0.76), 0.0064*	1 = reference	1.43 (0.90–2.27), 0.1297	1 = reference	0.99 (0.57–1.71), 0.9701
CLABSI with gram-negative bacteria	N	11	12	16	12	14	22
	ID / 1000 CL days (95%CI)	0.24 (0.12–0.43)	0.22 (0.11–0.39)	0.27 (0.15–0.43)	0.21 (0.11–0.36)	0.21 (0.12–0.35)	0.31 (0.20–0.48)
Compared to baseline in each study group	IRR (95%CI), p-value	1 = reference	0.92 (0.41–2.10), 0.8504	1 = reference	0.77 (0.37–1.63), 0.4995	1 = reference	1.50 (0.77–2.92), 0.2393
Baseline period included 12 months before the intervention was started. Parts of intervention period have been shown elsewhere (15). CLABSI, central line associated bloodstream infection. CL, central line. 95%CI, 95% confidence interval. ID, incidence densities per 1000 CL days. IRR, incidence rate ratios calculated by Poisson regression comparing intervention period to baseline period in each study group. CoNS, coagulase-negative staphylococci. ^a P-values based on comparison of intervention period to baseline period in each study group. ^b P-values were not shown because there were no differences between the three groups during the intervention period. * P-values < 0.05 were considered significant.

Characteristics of the study population stratified by study groups (chlorhexidine, octenidine, control) and periods (baseline and intervention period) did not differ between baseline and intervention periods in all groups as well as between the groups during the intervention period (Table 1 and Supplemental Table 1).

CLABSI with any pathogens

Incidence densities of ICU-associated CLABSI with any pathogen per study group during baseline and intervention periods are visualised in Table 1 and Fig. 2A. In the chlorhexidine group, the CLABSI rate at baseline was noticeably, but non-significantly higher (1.48 CLABSI with any pathogen / 1000 CL days) compared to the octenidine (1.26 CLABSI / 1000 CL days, p = 0.335) and the control group (1.20 CLABSI / 1000 CL days, p = 0.208).

The crude incidence rate ratios for CLABSI with any pathogen comparing the intervention and baseline periods showed a significant reduction in the chlorhexidine group, but no significant changes in the octenidine and control group (Table 1). In fact, incidence densities of the control group remained stable over the entire observation period (Table 1, Fig. 2).

Multivariable analysis adjusting for mechanical ventilation and length of stay confirmed the preventive effect of the daily bathing regime in the chlorhexidine, but not in the octenidine or control group when comparing intervention versus baseline periods for each study group (Table 2, Fig. 3A). The preventive effect of chlorhexidine was found in ICUs with high incidence densities at baseline, but was not detected in ICUs with low CLABSI rates at baseline (Table 3, Fig. 3B and C). Neither ICUs with high nor low CLABSI rates at baseline had a benefit from antiseptic bathing with octenidine. CLABSI rates even increased in ICUs with low CLABSI rates at baseline in the octenidine group (Table 3, Figure, 3B and C).

Table 2

Adjusted incidence rate ratios (aIRR) of intervention versus baseline periods for the outcome CLABSI with any pathogen, CLABSI with gram-positive pathogens, CLABSI with CoNS and CLABSI with gram-negative bacteria according to study group (post-hoc analysis).
		Chlorhexidine			Octenidine			Routine care (control arm)
Outcome		aIRR (95%CI)	P-value	P-value (Type III)	aIRR (95%CI)	P-value	P-value (Type III)	aIRR (95%CI)	P-value	P-value (Type III)
CLABSI with any pathogen
	Baseline period	1 = reference		0.0172*	1 = reference		0.5111	1 = reference		0.9190
	Intervention period	0.63 (0.46–0.87)	0.0055		1.17 (0.79–1.72)	0.4394		0.98 (0.60–1.58)	0.9193
	Mechanical ventilation use (per 1%)	1.02 (1.01–1.03)	0.0043	0.0420*	1.01 (0.99–1.02)	0.3808	0.4730	1.02 (0.99–1.04)	0.1505	0.1589
	Length of stay (per 1 day)	0.98 (0.87–1.10)	0.6778	0.6712	1.14 (1.06–1.22)	0.0003	0.1134	1.01 (0.89–1.15)	0.8716	0.8754
CLABSI with gram-positive bacteria
	Baseline period	1 = reference		0.0580	1 = reference		0.3077	1 = reference		0.9610
	Intervention period	0.55 (0.34–0.90)	0.0176		1.46 (0.86–2.50)	0.1651		0.99 (0.55–1.78)	0.9607
	Mechanical ventilation use (per 1%)	1.02 (1.00-1.03)	0.0280	0.0730	1.00 (0.99–1.02)	0.5746	0.6239	1.02 (0.99–1.04)	0.1495	0.1973
	Length of stay (per 1 day)	0.94 (0.86–1.04)	0.2440	0.2920	1.11 (0.98–1.25)	0.1172	0.2663	1.04 (0.92–1.18)	0.5404	0.5173
CLABSI with CoNS
	Baseline period	1 = reference		0.0359*	1 = reference		0.4452	1 = reference		0.9252
	Intervention period	0.38 (0.19–0.74)	0.0043		1.62 (0.63–4.17)	0.3134		1.02 (0.64–1.65)	0.9257
	Mechanical ventilation use (per 1%)	1.03 (1-1.05)	0.0295	0.0990	1.01 (0.99–1.02)	0.2205	0.2804	1.02 (1-1.04)	0.0604	0.1473
	Length of stay (per 1 day)	0.95 (0.88–1.03)	0.1786	0.2959	1.05 (0.87–1.27)	0.6020	0.6692	1.01 (0.88–1.17)	0.8531	0.8592
CLABSI with gram-negative bacteria
	Baseline period	1 = reference		0.6008	1 = reference		0.4507	1 = reference		0.2151
	Intervention period	0.79 (0.34–1.84)	0.5825		0.79 (0.46–1.37)	0.4067		1.5 (0.95–2.37)	0.0792
	Mechanical ventilation use (per 1%)	1.01 (0.98–1.04)	0.4426	0.5020	1 (0.98–1.03)	0.7811	0.7880	1.01 (0.97–1.04)	0.7374	0.7262
	Length of stay (per 1 day)	1.07 (0.95–1.21)	0.2633	0.3005	1.28 (1.2–1.36)	< .0001	0.0313	1.05 (0.82–1.36)	0.6844	0.7248
CLABSI, central line associated bloodstream infection. 95%CI, 95% confidence interval. aIRR, adjusted incidence rate ratios. Separate GEE models were based on monthly aggregated data, negative binomial distribution, accounted for clustering effects and were calculated with the log number of CL days as offset variable. Parameters considered in all models were invasive ventilation use and length of stay. * P-values (type III test) < 0.05 were considered significant

Table 3

Adjusted incidence rate ratios (aIRR) of intervention versus baseline periods for the outcome CLABSI with any pathogen stratified by high or low incidence densities (ID) of CLABSI at baseline (< or ≥ 0.8 CLABSI/1000 CL-days) according to study group (post-hoc analysis).
		Chlorhexidine			Octenidine			Routine care (control arm)
Outcome / Group		aIRR (95%CI)	P-value	P-value (Type III)	aIRR (95%CI)	P-value	P-value (Type III)	aIRR (95%CI)	P-value	P-value (Type III)
CLABSI with any pathogen
ICUs with low incidence density of CLABSI at baseline (< 0.8 CLABSI / 1000 CL days)		n = 11 ICUs			n = 13 ICUs			n = 12 ICUs
	Baseline period	0.88 (0.42–1.86)	0.7390	0.7373	2.59 (1.61–4.17)	< .0001	0.0383*	0.67 (0.3–1.52)	0.3390	0.3626
	Intervention period
	Mechanical ventilation use (per 1%)	1.01 (0.99–1.03)	0.4830	0.4275	1.01 (0.98–1.04)	0.3760	0.3927	0.99 (0.96–1.03)	0.7080	0.7800
	Length of stay (per 1 day)	0.74 (0.53–1.04)	0.0830	0.1320	1.05 (0.65–1.68)	0.8520	0.8602	1.13 (0.93–1.38)	0.2070	0.3666
ICUs with high incidence density of CLABSI at baseline (≥ 0.8 CLABSI / 1000 CL days)		n = 13 ICUs			n = 11 ICUs			n = 12 ICUs
	Baseline period	1 = reference			1 = reference			1 = reference
	Intervention period	0.61 (0.42–0.88)	0.0080	0.0226*	0.98 (0.58–1.64)	0.9380	0.9365	1.06 (0.63–1.78)	0.8210	0.8242
	Mechanical ventilation use (per 1%)	1.02 (1-1.03)	0.0160	0.0912	1 (0.99–1.02)	0.8200	0.8405	1.01 (0.99–1.02)	0.4090	0.4278
	Length of stay (per 1 day)	0.95 (0.85–1.06)	0.3540	0.3631	1.09 (1.02–1.17)	0.0100	0.2590	1.14 (1.02–1.27)	0.0250	0.0505
CLABSI, central line associated bloodstream infection. 95%CI, 95% confidence interval. aIRR, adjusted incidence rate ratios. Separate GEE models were based on monthly aggregated data, negative binomial distribution, accounted for clustering effects and were calculated with the log number of CL days as offset variable. Parameters considered in all models were invasive ventilation use and length of stay. * P-values (type III test) < 0.05 were considered significant.

CLABSI with gram-positive bacteria

For CLABSI with gram-positive bacteria, the incidence densities per study group and period are visualised in Table 1 and Fig. 2B. The crude incidence rate ratios showed a significant reduction of CLABSI with gram-positive bacteria between intervention and baseline period in the chlorhexidine group, a significant increase in the octenidine group, and no change in the control group (Table 1, Fig. 2B). Adjusted incidence rate ratios of CLABSI with gram-positive bacteria, however, found no significant differences between intervention and baseline period in any study group (Table 2).

CLABSI with CoNS

For CLABSI with CoNS, the crude incidence rate ratio was significantly reduced in the chlorhexidine group, but not in the octenidine or control group (Table 1). These findings were confirmed by adjusted incidence rate ratios (Table 2).

CLABSI with gram-negative bacteria

In all groups, no changes between intervention and baseline periods were detected for CLABSI with gram-negative bacteria neither in the crude nor in the adjusted analysis (Tables 1 and 2).

Sensitivity analysis

All results of the multivariable analyses for CLABSI with any pathogen were stable in the sensitivity analyses adjusting for additional potential confounders (medical ICU, use of antibiotic-coated CL, chlorhexidine-impregnated dressings and needless devices, Supplemental table 2).

This is a post-hoc before-after analysis of the first comparative multi-center cRCT that examined antiseptic bathing with chlorhexidine and octenidine for CLABSI prevention in ICUs. In the post-hoc analysis comparing baseline and intervention periods (before-after), chlorhexidine-impregnated cloths significantly reduced ICU-associated CLABSI by about 40%. Decolonisation with chlorhexidine had no effect on CLABSI caused by gram-negative pathogens, but prevented CLABSI caused by gram-positive bacteria, mainly CoNS. In contrast, octenidine wash mitts did not show a preventive effect on CLABSI, neither caused by gram-positive nor gram-negative bacteria. At the same time CLABSI rates remained stable in the control group over the entire observation period.

Our post-hoc analysis confirmed findings of previous studies that showed a preventive effect of chlorhexidine-impregnated cloths on CLABSI rates in ICU patients (7, 11, 12, 28–30). Most clinical studies that demonstrated a preventive effect of chlorhexidine-impregnated cloths started with CLABSI rates at baseline ≥ 3.0 CLABSI / 1000 CL days (compared to the median of 0.8 CLABSI / 1000 CL days in our trial) (7, 28–30). In our subgroup analysis, we stratified ICUs according to lower CLABSI rates (below the median of 0.8 CLABSI / 1000 CL days) and higher CLABSI rates (above the median). This analysis demonstrated that chlorhexidine bathing had a preventive effect in ICUs with high CLABSI rates, while this effect was not detectable in ICUs with low CLABSI rates at baseline.

Octenidine wash mitts did not reduce CLABSI of ICU patients in our study. Thus, we could not confirm the promising results of previous single-center observational trials (18, 19). One study showed that universal decolonisation of ICU patients with octenidine-containing wash mitts in combination with octenidine nose gel reduced the incidence of primary and secondary ICU-acquired BSI in medical ICUs (18). We can only speculate about reasons for the lacking preventive effect of octenidine in the CLIP-ID study. Here, we did not use any antiseptic application for the nose, the primary outcome was CLABSI (not including secondary BSI), and the proportion of medical ICUs participating in our trial was below 10%. Further, the protocol for correct application of octenidine wash mitts was not the same as for chlorhexidine. Among other differences, use of any skin care product after daily antiseptic bathing was strictly forbidden in the chlorhexidine, but not in the octenidine group. For octenidine wash mitts, the manufacturer allowed the use of any product 30 seconds after its application. Further, while chlorhexidine-impregnated cloths contained 2% (20 mg/ml) chlorhexidine, octenidine wash mitts were impregnated with 0.08% octenidine (0.8 mg /ml). Even though, in vitro octenidine is superior in its antiseptic efficacy compared to chlorhexidine, the differences in concentration of these ready-to-use products might be relevant (31).

Interestingly, the reduction of CLABSI in the chlorhexidine group could mainly be attributed to CLABSI with CoNS. At the same time, the increase of CLABSI in the octenidine group was also mainly due to CLABSI with gram-positive bacteria including CoNS. Even though CoNS are considered pathogens of low virulence, catheter-related BSI or bacteremia with CoNS have been associated with severe clinical outcomes including increased duration of hospitalization, therapy related costs and morbidity (32). Further, CoNS are one of the most frequent causes of CLABSI, also confirmed by our trial. In consequence, prevention of CLABSI with CoNS is clinically relevant and should be taken seriously. CoNS are one of the main sources of blood culture contamination (33). However, we consider the risk of misclassification as low in our trial as the definition of CLABSI with CoNS required the detection of the same CoNS in at least two separate blood samples and the presence of at least one symptom, e.g. fever or hypotension (26).

Tolerability of chlorhexidine-impregnated cloths and octenidine wash mitts by patients was high and has been reported in detail elsewhere (15). We performed sensitivity analyses to test the robustness of our data. Results were stable in all sensitivity analyses.

Strength and limitations

The preventive effect of chlorhexidine-impregnated cloths presented here is based on a post-hoc before-after analysis. The a priori analysis of this cRCT found no significant differences of CLABSI rates between the intervention groups (chlorhexidine and octenidine group) and the control group during the intervention period (15). However, there is a high likelihood that our main analysis was underpowered as CLABSI rates were 40% lower than initially expected for our sample size calculation (15). A controlled before-after analysis provides several advantages: First, adding a pre-test (before period) usually increases the power and precision of statistical tests (34). Further, it allows identifying initial differences between the groups (34). All important covariates tested (e.g. LOS, CL use, mechanical ventilation) did not differ between the three study groups and two study periods. However, the chlorhexidine group started with non-significant but higher CLABSI rates at baseline compared to the octenidine and control group. The pretest-posttest-control-design allows estimates of treatment effectiveness even when treatment and control group are not equivalent (34). In consequence, we considered the before-after analysis as most suitable to overcome this non-significant imbalance across the groups. Third, the before-after design allows studying the effect of the intervention at different sublevels of the pre-test. In our stratified analysis, we identified ICUs with CLABSI rates at baseline above the median to benefit from chlorhexidine bathing, while ICUs with lower rates at baseline did not. This important observation was not available by the post-test only control group design (15). Convincingly, the control group applying water and soap as routine care did not change during the entire observation period. Thus, the occurrence of systematic or structural changes (e.g. changes of guidelines, medical improvements, etc.) that might have an effect on CLABSI rates in the CLIP-ID wards during the study period is highly unlikely. Before-after analysis is an appropriate approach for randomised controlled trials that has been used before in highly published decolonisation trials (6, 8, 35).

Additional limitations of this cluster-randomised decolonisation trial have already been discussed elsewhere (15).

Generalisability

The majority of ICUs that reduced their CLABSI rates by daily chlorhexidine bathing according to the post-hoc analysis started with at least 0.8 CLABSI / 1,000 CL days (median). Thus, chlorhexidine bathing seems to be more effective in ICUs above a certain CLABSI rate and might not be transferable to ICUs with lower rates.

Neither ICUs with high nor low CLABSI rates at baseline had a benefit from antiseptic bathing with octenidine.

Type of ICU seems not to have an impact on the effectiveness of antiseptic bathing.

This post-hoc analysis suggests that the application of 2% chlorhexidine-impregnated cloths might have a preventive effect on CLABSI in ICUs with ≥ but not < 0.8 CLABSI / 1000 CL days at baseline. In contrast, 0.08% octenidine wash mitts did not reduce CLABSI rates in ICUs.

aIRR, adjusted incidence rate ratio

BSI, bloodstream infection

CHG, chlorhexidine gluconate

CL, central line

CLABSI, central-line associated BSI

CLIP-ID, climate and pathogens – impact of decolonisation

CoNS, coagulase-negative staphylococci

95%CI, 95% confidence interval

cRCT, cluster randomised controlled trial

FAQ, frequently asked question

GEE, generalised estimating equation (model)

HAI, healthcare-associated infection

ICU, intensive care unit

ICU-KISS, German national surveillance system for nosocomial infections in intensive care units

ID, incidence density

IRB, institutional ethical review board

IRR, incidence rate ratio

PM, pooled mean

SOP, standard operating procedure

Ethics approval and consent to participate

This study was conducted in compliance with the principles of the Declaration of Helsinki. The institutional ethical review board (IRB) of Charité Universitätsmedizin Berlin (processing number EA1/093/16) granted its approval for this trial at June 2, 2016. The IRB granted a waiver of written informed consent as the study fulfilled all criteria of a cluster-randomised controlled trial (cRCT).

Consent for publication

Not applicable. This study did not include any individual patient data, but analysed aggregated data only. Availability of data and materials

The datasets generated and analysed during the current study are not publicly available as data was collected by the German nosocomial infections surveillance system of intensive care units “ICU-KISS” hosted by the National Reference Center for Surveillance of Nosocomial Infections. The National Reference Center for Surveillance of Nosocomial Infections is committed by a non-disclosure agreement with the hospitals voluntarily participating in ICU-KISS on a confidential basis. It is illegal to publish unaggregated data that enables identification of individual hospitals directly or through a third party. Data sets are available from the National Reference Center for Surveillance of Nosocomial Infections Data Access Committee on reasonable request. Decisions on data requests will consider planned data use, compliance as well as measures for protection of privacy and data security. No individual ward-level results, only aggregated data (e.g. counts, distributions) may be provided. Scientists may send their statement of interest in the trial data to: Data Access Committee Nationales Referenzzentrum (NRZ) für Surveillance von nosokomialen Infektionen am Institut für Hygiene und Umweltmedizin Charité-Universitätsmedizin Berlin ([email protected]).

Competing interests

All authors have no conflicts of interest to declare. On behalf of all authors, the corresponding author states that there is no conflict of interest. The German Ministry of Education and Research (funder) and companies (Sage Products / Stryker, Schülke) funding products and the investigation of tolerances to chlorhexidine and octenidine by an independent laboratory had no role in study design, data collection and analysis, data interpretation, the decision to publish, or the preparation of the manuscript.

Funding

The CLIP-ID trial was funded by the German Federal Ministry of Education and Research within the scope of the InfectControl consortium (03ZZ0807A). Sage Products / Stryker and Schülke provided the (antiseptic) products for the intervention and funded the investigation of tolerances to chlorhexidine and octenidine by an independent accredited contract laboratory.

Authors' contributions

Funding acquisition, conceptualization and supervision were provided by P.G. and C.G. F.S, M.B., J.C., L.A.D., P.G., S.W., J.G. and C.G. developed and / or applied the methods. F.S., L.A.D. and C.G. were responsible for formal analysis and investigation. L.A.D. wrote the main manuscript text and prepared / adjusted figures 1 - 3. F.S. prepared figures 2 - 3. All authors reviewed and edited the main manuscript text.

Acknowledgments

We express our gratitude to all infection control practitioners, nurses, healthcare staff and physicians from all ICUs participating in the CLIP-ID trial. We thank the manufacturer’s the (antiseptic) products applied in this trial, Sage Products / Stryker and Schülke, for their kind support.

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No competing interests reported.

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Central-line associated bloodstream infections in intensive care units before and after implementation of daily antiseptic bathing with chlorhexidine or octenidine - A post-hoc analysis of a cluster-randomised controlled trial

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Abstract

Figures

Background

Methods

Trial design and participants

Interventions

Outcomes

Sample size

Randomisation and masking

Statistical analysis

Sensitivity analysis

Results

CLABSI with any pathogens

CLABSI with gram-positive bacteria

CLABSI with CoNS

CLABSI with gram-negative bacteria

Sensitivity analysis

Discussion

Strength and limitations

Generalisability

Conclusion

Abbreviations

Declarations

References

Additional Declarations

Supplementary Files

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