The study follows the STROBE Statement for reporting observational studies (36) guidelines.
Study design and settings
A cross-sectional study design was applied, and data were collected from July 2017 to February 2018 among suspected TB patients in Kassala State. The Kassala State is one of the eighteen states of Sudan, situated in the eastern region of the country. The State is divided into eleven localities and is covering an area of 42,282 square kilometres. In 2018, the population of the State was estimated at 2.5 million based on the 2008 population census. According to the State TB program, the prevalence of TB was about 71 per 100000 population in 2018. The TB/HIV burden among TB patients appears to be high, with an estimated 18.6% of the TB patients being infected with HIV (9). At the time of the study, there were twenty-two TBMUs providing diagnostic services and treatment for suspected TB patients. All TBMUs offered HTC services.
Study population and recruitment
A three-sampling stage was performed. The first stage was simple random sampling to select four localities from the sampling frame of eleven localities in Kassala State. The second stage was a random selection of one TBMU from each selected locality. A total of four TBMUs were selected. The third was on-site systematic sampling for selection of participants from each TBMU where the first participant was randomly selected from the clinic registers, and then every third was interviewed using a constant numeric interval. The number of selected participants for sampling from each TBMU was proportional to the number of suspected TB patients attending at that TBMU. Any participant who refused to participate for any reason was replaced by the immediate next one until we reached the required sample size. All the suspected TB patients who were attending TBMUs for diagnosis purposes during the study period were eligible for this study. We included patients suspected of TB who aged 18-64 years in the selected TBMUs. A sample size of 383 participants was computed by sample estimation for correlation with pre-specified 95% confidence interval (37). This sample size allows estimation of a correlation of .05 with a width of.10.
The independent variable of this study was the intention to use HTC services in TBMUs in Kassala State in the next three months. The explanatory variables were behavioural beliefs, normative beliefs, and control beliefs regarding the use of HTC services in the TBMUs in the next three months, risk perception of HIV infection, and exposure to HTC services during the last year. Information on demographic and socioeconomic variables, including age, gender, residence, marital status, education, working, HIV and HTC related-knowledge, were also collected.
Data collection and Measurements
Trained data collectors used a structured questionnaire to collect data from the participants. All respondents provided consent to participate before included in the study. Uneducated participants were interviewed, and educated participants fill out the questionnaire by themselves.
The questionnaire was based on the RAA (29). The statements used to measure the beliefs in this study were developed from a literature review (38-42) and elicitation study conducted in the study population. The elicitation study is essential to identify beliefs (43) that associated with the intention to use HTC services.
The intention to use HTC services was measured by three items which were: (1) I intent, to use HTC services in the next three months, (2) I expected to use HTC services in the next three months and (3) I want to use HTC services in the next three months, and were each measured on a 7–point Likert scale. The higher score indicated a more positive intention.
The behavioural beliefs were measured by asking the participants to rate five statements regarding using HTC services in the next three months. The statements were: (1) "If I use the HTC services I will know my HIV status", (2) "My using HTC services facilitates my treatment if I have a HIV positive test result", (3) "If I use the HTC services I could prevent infecting my family from HIV infection", (4) "If I use the HTC services I would feel worries about my HIV test result", and (5) "If I use the HTC services I would have information about HIV infection". The participants replied on a seven-point Likert scale ranging from 1(unlikely) to 7 (likely).
The normative beliefs were evaluated by using four items which were answered on a seven-point Likert scale (with disagree (1) and agree (7) as anchors). The four items were: (1) "My doctor thinks I should use the HTC services in the next three months", (2) "My friends think I have to use the HTC services in the next three months", (3) "My partner thinks I should use HTC services in the next three months.", and (4) "My parent thinks I should use HTC services in the next three months."
Five items assessed the control beliefs: (1) "Health care providers keep my HIV test result confidential", (2) "I would fear to be stigmatized if I get a HIV positive test result", (3) "I would fear losing my partner if I have HIV positive test result", (4) "I would find it difficult to disclose my HIV positive test result to others", and (5) "I could have the cost to reach HTC services". Responses were on a seven-point unipolar (unlikely (1) -likely (7)) scale.
Two items assessed the perceived HIV risk: "I think I may be infected with the HIV infection", and “I think my partner may be infected with the HIV infection", scored on a seven-point (disagree (1)-agree (7)) scale.
Previous exposure to HTC services was measured by one item:" In the last year I had an experience with HTC services". Responses ranged from disagree (1) to agree (7).
HIV and HTC related knowledge was assessed by five questions adapted from previous studies (44-46). The question were : (1) healthy-looking person can be infected with HIV, (2) HIV infection transmitted through sexual intercourse, (3) HIV infection can be prevented by using a condom, (4) HTC is provided at TB facilities, and (5) HTC is important for TB and suspect TB patients. Questions were answered using 'Yes', 'No' and 'Do not know'. Yes, answer coded 1 and No or Do not know code as 0.