Study population
We recruited 51 stable patients with CF at a routine visit and 30 patients treated with IV antibiotherapy. All characteristics of the patients are summarized in Tables 1 and 2.
Table 1
Characteristics of the patients with CF in stable condition
Subjects, n | 51 |
Sex (F/M) | 14/37 |
Age, yrs | 31 ± 14 |
Children (< 18 yrs)/Adults | 9/42 |
F508del/F508del (yes/no) | 25/26 |
Sweat Chloride, mmol/L | 106 (29; 140) |
Pancreatic sufficiency (yes/no) | 14/37 |
Pseudomonas aeruginosa chronic infection (yes/no) | 19/32 |
Diabetes (yes/no) | 9/42 |
Smokers (yes/no) | 4/47 |
BMI, kg/m² | 21.05 (14.65; 33.80) |
FEV1, L | 2.69 ± 1.17 |
FEV1, %PV | 74.21 ± 22.37 |
1STST, n | 34 (17; 68) |
1STST, %PV 26 | 79 (7; 142) |
1STST, nxkg | 2101 ± 657 |
MVCQ, N-m | 78.64 (23.21; 170.34) |
MVCQ, %PV 28 | 56.73 ± 26.21 |
Data are mean ± SD if parametric or median (min; max) if non-parametric data (Kolmogorov and Shapiro-Wilk tests). Definition of abbreviations: n, number; F, female; M, male; yrs, years; mmol/L, millimoles per liter; BMI, body mass index; kg/m2; kilogram divided by the square meter; FEV1, forced expiratory volume in one second; L, liter; PV, predicted values ; 1STST, the one-minute sit-to-stand test; nxkg, number of repetitions as a product of bodyweight expressed in kilogram ; MVCQ, maximal isometric voluntary contraction of the quadriceps; N-m, Newton-meter.
Table 2
Characteristics of the patients with CF receiving IV antibiotics
Subjects, n | 30 |
Sex (F/M) | 12/18 |
Age, yrs | 36 ± 14 |
Children (< 18 yrs)/Adults | 5/25 |
F508del/F508del (yes/no) | 14/16 |
Sweat Chloride, mmol/L | 100.00 (23.40; 127.40) |
Pancreatic sufficiency (yes/no) | 10/20 |
Pseudomonas aeruginosa chronic infection (yes/no) | 15/15 |
Diabetes (yes/no) | 6/24 |
Smokers (yes/no) | 3/27 |
BMI, kg/m² | 20.51 (17.63; 31.09) |
FEV1, L | 1.98 ± 0.81 |
FEV1, %PV | 56.79 ± 14.70 |
1STST, n | 33 (18; 57) |
1STST, %PV 26 | 69.23 (40.91; 125.53) |
1STST, nxkg | 1976 (1035; 3477) |
MVCQ, N-m | 73.48 ± 31.34 |
MVCQ, %PV 28 | 50.15 (23.86; 142.26) |
CRP, mg/L (n = 29) | 3 (1; 133) |
IgG, g/L (n = 27) | 10.50 (6.30; 25.10) |
Chest X-Ray – new infiltrate (yes/no) (n = 13) | 4/9 |
Exacerbation/Elective | 11/19 |
Hospital/Home | 16/14 |
Steps, n/24h | 8371.12 ± 4463.73 |
Data are mean ± SD if parametric or median (min;max) if non-parametric data (Kolmogorov and Shapiro-Wilk tests). N is specified when data are missing. Definition of abbreviations: n, number; F, female; M, male; yrs, years; mmol/L, millimoles per liter; BMI, body mass index; kg/m2; kilogram divided by the square meter; FEV1, forced expiratory volume in one second; L, liter; PV, predicted values ; 1STST, the one-minute sit-to-stand test; nxkg, number of repetitions as a product of bodyweight expressed in kilogram ; MVCQ, maximal isometric voluntary contraction of the quadriceps; N-m, Newton-meter; CRP, C-reactive protein; mg/L, milligram per liter; IgG, G-immunoglobulin; g/L, gram per liter; n/24h number of steps per day.
Peripheral muscular strength and functional exercise capacity in children and adults with CF in stable condition
The 1STST was reduced (79% (7;142) of the predicted values (%PV)) as well as the MVCQ to 57%PV ± 26. A moderate correlation between the 1STST expressed in number of repetitions as a product of the bodyweight and the MVCQ was observed (Figs. 1A, 1B). Moreover, we found a moderate correlation between the 1STST and the severity of the disease assessed by the forced expiratory volume in one second (FEV1) (Fig. 1C). No correlation was found between the 1STST expressed in number of repetitions and the MVCQ in N-m (r = 0167). Except for the MVCQ which was significantly lower in Pseudomonas aeruginosa chronically infected patients (Psa (+): MVCQ 69.57N-m (34.70; 161.30), Psa (-): MVCQ 90.74N-m (23.22; 170.30), p = 0.0349 and Psa (+): MVCQ 41.30%PV (17.20; 83.53), Psa (-): MVCQ 61.91%PV (18.26; 113.70), p = 0.0079), we did not observe any differences in 1STST and MVCQ regarding to the genotype, the pancreatic status or the patient’s microbiology (Figure S1).
Peripheral muscular strength and functional exercise capacity in children and adult patients with CF treated with IV antibiotherapy
The average duration of the IV antibiotherapy was 16.2 days. The initial 1STST was decreased (69%PV (41; 126)) as well as the MVCQ (50%PV (24; 142)). Thirty-six percent of the patients presented an acute exacerbation at the beginning of the IV antibiotherapy and fifty-three percent of the patients were hospitalized according to the criteria previously described in the methods. This treated population was rather moderately active with a mean number of steps per day of 8371/24h ± 4464.
The 1STST significantly improved after the antibiotic treatment (before: 1814nxkg (978; 3612); after: 2020nxkg (1287; 4089), p < 0.0001) (Fig. 2A). This increase is also observed when 1STST is expressed as number of repetitions or percentage of predicted values (Figure S2). No correlation between the gain of 1STST (expressed as number of repetitions or percentage of predicted values) and the BMI was present (Figure S2). Thirteen patients out of the 30, showed an improvement of more than 5 repetitions after IV antibiotics which is considered as clinically relevant (Figure S3) 20. Concerning the improvement of MVCQ, only a positive trend was shown (Figs. 2B-C). The increase of 1STST was moderately correlated to MVCQ improvement (r = 0.441; p = 0.015) (not shown). As expected, after the antibiotherapy, FEV1 and BMI were enhanced (Figs. 2D-2F). Of note, we did not see any correlation between the gain of the 1STST or the MVCQ and the gain of the FEV1 or physical activity of the patients. No significant difference was found regarding to the gain in the 1STST depending on the number of steps (> 5000 steps/day is considered as active and < 5000 steps/day as sedentary person).
Comparison between the clinical characteristics before and after IV antibiotic treatment regarding to the localization (home versus hospital).
No significant difference in the severity of the disease was observed between patients treated at home or at hospital except for their age (Table S1). However, hospitalized patients tended to show a more severe profile (genotype, sweet chloride, pancreatic insufficiency, Pseudomonas aeruginosa chronic infection, BMI, FEV1 and proportion of exacerbations). Both hospitalized and home treated patients significantly improved after the IV antibiotherapy regarding to the 1STST (nxkg). We found a significant greater improvement in the 1STST in hospitalized patients (22% (-16; 43) versus 6% (-11; 88), p = 0.0106) compared to patients treated at home whereas no significant change in the MVCQ was shown (7% (1; 33) versus 7% (-10; 35), p = 0.4) (Figs. 3A, 3B). Physical activity of hospitalized patient was significantly lower than patients treated at home (Fig. 3C). The mean number of steps per day was lower in hospital than at home (5402/24h (451; 14544) versus 9090/24h (3641; 16924), p = 0.0061) (Fig. 3C). No significant differences were assessed regarding to FEV1 or BMI improvement according to the localisation of the IV antibiotherapy. (Figs. 3D-F).
Comparison between clinical characteristics before and after IV antibiotic treatment regarding to the indication (elective versus exacerbation).
No significant difference in age neither in the severity of the disease was observed between elective or acute IV antibiotherapy (Table S2). However, exacerbated patients tended to show a lower lung function and a higher inflammatory profile at admission than elective patients and they were preferentially hospitalized. The gain in 1STST or MVCQ was not higher in exacerbated patients in comparison to elective patients (Figs. 4A, 4B). The 1STST significantly improved in both groups after the IV antibiotherapy. Physical activity of exacerbated patient tends to be reduced in comparison to elective patients (Fig. 4C). Contrarily to BMI, a significant difference was observed in the FEV1 improvement according to the indication of the IV antibiotherapy. (Figs. 4D-F).