Study design and setting
A quasi-experimental (pre- and post-test) design, with switching replication, was used for this study. There was an intervention group and a comparison group. A self-administered structured questionnaire was used to determine the nurses’ knowledge and practices concerning TBIC. It was administered to both groups before the intervention (baseline, T0), after which the intervention group was exposed to the educational programme. The same cohorts of nurses in both groups were followed up and the questionnaire was again administered 6 months later (T1) as illustrated below (Figure 1). After the second data collection wave, for public health and health systems considerations, the comparison group also received the training. Then six months later, final data collection was conducted (T2).
Figure 1: Flow diagram of the study
The study was conducted in Ibadan, the capital city of Oyo State, South-West Nigeria. It is the third largest metropolitan area in Nigeria, and the largest by geographical area (3,080 km2) with an estimated 2011 population of about 3,034,206 (density of 985/km2) [28,29]. Oyo State has the third highest TB burden in Nigeria, with 6901 cases reported in 2017 .
Study population and sample
Nurses who work at two secondary health facilities in two local government areas (LGAs), Ring Road State Hospital (Ibadan South-West LGA) and Adeoyo Maternity Teaching Hospital (Ibadan North LGA) were purposively selected to constitute the study population. The LGAs are non-contiguous and were selected to avoid the effect of contamination. Ibadan North has one tertiary health facility, one public secondary and 11 primary health centres (PHCs) while there are 3 public secondary facilities and 26 PHCs in Ibadan South-West. From available administrative data at the study sites, 173 and 217 nurses respectively at these facilities made up the study population (total = 390). With an expected moderate effect size (ES>0.50<0.80) in the TBIC knowledge of the nurses, a significance level of 5% and power of 80%, the study required at least 32 participants in each group . However, because of the public health and health system considerations of the educational intervention, all available nurses at the study sites were encouraged to participate in the study. One hundred (100) nurses were eventually enrolled into the study at each site (total = 200).
A mixed-approach educational intervention was implemented. This approach to training has been proven to be more effective in improving knowledge and altering professional practice of nurses and other HCWs [26,32]. The training, which took place over a 3-hour period, consisted of didactic lectures using Microsoft PowerPoint presentations prepared using WHO and CDC materials on TBIC; a 14-minute video presentation titled, Implementing TB Infection Control in Outpatient Settings, produced by CDC; as well as sessions for general discussion and practical demonstration [33–35]. A session on hand hygiene was incorporated into the training as this has been recommended by WHO for implementation in the context of general infection control . To serve as reminders, printed copies of the lecture, as presented, were provided to the nurses after the training session. Also, CDC-designed educational materials (signages, posters and stickers on TBIC workplace practices) were conspicuously displayed at the facility after the training. Adjustments in the training time was made to accommodate the nurses’ work schedule in order to train every one of them: 5 training sessions were held for a group of 18–25 nurses each time, including sessions that were conducted in the evening for the nurses on night shift. Generally, the educational materials covered the following topics concerning TB: cause, transmission, symptoms and signs, infectiousness, risk factors and TB infection control measures. The comparison group also received the same training 6 months after the intervention group, with the same process being repeated.
The self-administered questionnaire used for this study had a section on socio-demographics, as well as scales on the TBIC-related knowledge and practices of the nurses. These scales were adapted from an instrument used by Kanjee et al.  to study TBIC in a high drug-resistance setting in South Africa. The knowledge scale contained 33 items, with each having response options of "true”, "false”, or "I don’t know”. Each correct answer had a score of “1” and an incorrect answer, "0” while "I don‘t know” was considered an incorrect answer. The knowledge and practice scales had a maximum possible scores of 33. The TBIC practice scale had 6 items which measured self-reported frequency of adherence to various TBIC practices. It was scored using a 5-point Likert-type scale: “never” (1 point), “rarely” (2), “sometimes” (3), “often” (4), and "always" (5), giving it a maximum possible score of 30.
Two research assistants and a supervisor were recruited and trained for the study. After explaining the purpose of the study to the participants, each of them that consented to take part in the study received a copy of the information leaflet, consent form and study questionnaire. After signing the consent, the self-administered questionnaire was issued out to each participant and returned after completion in May 2014 (wave 1). Six months after the training was conducted on the intervention group, the questionnaire was again administered on both groups in November 2014 (wave 2). After this, the comparison group received the intervention. At the end of another six months (i.e. 12 months after commencement of the study), the questionnaire was administered on both groups again in May 2015 (wave 3).
Data collected was analyzed using SPSS Statistics version 24. Descriptive statistics were used to show the socio-demographic characteristics of the nurses and their levels of knowledge and practice regarding TBIC. Independent t-test and chi-square test (χ²) respectively were utilized for comparison of the continuous and categorical variables between the intervention and comparison groups. The knowledge and practice scores were presented as percentages (%). In addition, they were categorized into “good” and “poor” scores using cut-off points of 80% and 100% for knowledge and practice respectively. The cut-off for good practice score was set at 100% because optimal performance of TBIC measures is essential to minimize the nurses’ risk of contracting TB. Independent t-test was also utilized to demonstrate significant differences between the mean scores of both groups at different time points. The level of statistical significance was set at p<0.05. The effect size (Cohen’s d) was calculated using the 6th month measurement to demonstrate the magnitude of the change in the knowledge score of the intervention group resulting from the educational programme.
The study was approved by Sefako Makgatho Health Sciences University Research Ethics Committee (MREC/H/271/2013: PG) and Oyo State Ministry of Health Research Ethical Review Committee in Nigeria (AD 13/479/557). Permission was obtained from Oyo State Hospitals Management Board and the management of Adeoyo Maternity Teaching Hospital and Ring Road State Hospital, both in Ibadan, Oyo State, Nigeria. Participation in the study was completely voluntary and measures were taken to ensure privacy and confidentiality of the participants, and written informed consent was obtained from each participant.