Factors associated with Hepatitis B screening and completion of vaccination schedule among young psychoactive substance users in Kampala's informal settlements, Uganda

Background Young psychoactive substance users exhibit high-risk behaviours which can increase their risk to Hepatitis B infection. However, there is limited information on screening, and completion of the Hepatitis B vaccination schedule among young psychoactive substance users in informal settlements. Therefore, this study determined the factors associated with Hepatitis B screening, and completion of the Hepatitis B vaccination schedule among young psychoactive substance users in Kampala’s informal settlements, Uganda. Methods A cross-sectional study design was used. Respondent driven sampling was used to enroll 768 respondents from 12 informal settlements. Data were collected using a structured questionnaire and analysed using Stata version 14. A “modified” Poisson regression analysis was done to determine the factors associated with Hepatitis B screening while logistic regression was used to determine the factors associated with completion of the Hepatitis B vaccination schedule. Results Out of the 768 respondents, only 13.3% had ever screened for Hepatitis B and 2.7% had completed the Hepatitis B vaccine schedule. Being a female (aPR 1.61, 95% CI: 1.11-2.33), earning a monthly income >USD 136 (aPR 1.78, 95% CI: 1.11-2.86); completion of the Hepatitis B vaccination schedule (aPR 1.85, 95% CI: 1.26-2.70); lack of awareness about the recommended Hepatitis B vaccine dose (aPR 0.43, 95% CI: 0.27-0.68); and the belief that the Hepatitis B vaccine is effective in preventing Hepatitis B infection (aPR 3.67, 95% CI: 2.34-5.73) were associated with “ever screening” for Hepatitis B. Knowledge about the recommended Hepatitis B vaccine dose (aOR 0.06, 95% CI: 0.01-0.35); “ever screening” for hepatitis B (aOR 9.68, 95% CI: 2.17-43.16) and the belief that the hepatitis B vaccine is effective in preventing Hepatitis B infection (aOR 11.8, 95% CI: 1.13-110.14) were associated with completion of the Hepatitis B vaccination schedule. Conclusion Our findings indicate a low prevalence of Hepatitis B screening and completion of the Hepatitis B vaccination schedule among young psychoactive substance users


Background
Globally, the consumption of psychoactive substances is an increasing public health problem. It was estimated that in 2016, 275 million people used psychoactive substances such as cannabis (marijuana), amphetamines, opioids and cocaine. Among these, at least 31 million suffered from drug use disorders (1). The use of psychoactive substances is associated with high risk behaviours such as having multiple sexual partners, unprotected intercourse, drug-sex exchanges and sharing of drug preparation equipment such as used needles (2). These behaviours increase the risk of transmission of Hepatitis B virus (HBV) infection (2). Hepatitis B is a potentially life threatening infection caused by HBV (3). It accounts for over 780,000 deaths each year (3). Hepatitis B infections are often associated with hepatocellular carcinoma, liver cirrhosis, inflammation and at times death (4,5). These outcomes pose a serious economic burden on both the healthcare system and households (6)(7)(8).
Owing to the public health significance of Hepatitis B, the World Health Organisation (WHO) instituted the first guidelines for the prevention, care and treatment of persons living with chronic Hepatitis B infection and guidelines for Hepatitis B testing which emphasized testing for high-risk groups such as psychoactive substance users (5). The aim of these guidelines is to strengthen and expand the existing prevention, care and treatment strategies including Hepatitis B testing and vaccination (5,9).
Screening and vaccination are the cornerstone of Hepatitis B prevention. Hepatitis B screening is the gateway for access to both prevention, care and treatment services (9). It presents an opportunity for health education, counselling and provision of prevention commodities such as sterile needles to injecting psychoactive substance users (9). On the other hand, vaccination can reduce the incidence of Hepatitis B infections (10,11).
WHO recommends that high-risk groups such as psychoactive substance users including injection drug users should be tested for and vaccinated with three doses of the recombinant deoxyribonucleic acid or plasma-derived Hepatitis B vaccine (3). Despite the recommendations, Hepatitis B screening and vaccination programs targeting psychoactive substance users are still uncommon especially in informal settings (12). Even where services are available, psychoactive substance users often shy away from these programs due to the costs involved and fear to commit to the vaccination schedule (12,13). Consequently, only a small percentage of individuals with Hepatitis B either know their serostatus or are able to access the treatment, care and support they need (14). The majority often report with the advanced disease (5).
Young psychcoactive substance users (defined as individuals aged 10-24 who use psychoactive substances) in informal settlements are not different. Due to their low socioeconomic status and limited access to healthcare services (15)(16)(17)(18)(19)(20), they are more likely to be unaware of their Hepatitis B status, and unvaccinated. Nonetheless, there is still limited evidence on the prevalence and factors associated with Hepatitis B screening and competition of the Hepatitis B vaccination schedule among young psychoactive substance users in informal settlements. Yet, these engage in high-risk sexual behaviours that can potentially increase transmission of blood borne infections including Hepatitis B (21). Understating the predictors of Hepatitis B screening and vaccination among young psychoactive substance users would be an important stride to fulfilling the targets of the global hepatitis response strategy. The strategy specifically targets a 90% reduction in new cases of chronic Hepatitis infection and 65% reduction in deaths from chronic hepatitis B by 2021 (22).
This study utilised the Knowledge Attitude and Practice model (23,24) to determine the factors associated with Hepatitis B screening and vaccination among young psychoactive substance users in Kampala's informal settlements, Uganda. This model has also been applied in other Hepatitis B studies to understand the factors associated with screening and vaccination status among other highrisk groups (25)(26)(27). The information generated by this study can be used to inform Hepatitis B prevention programs.

Materials And Methods Scope and Design
This cross-sectional study was conducted in the informal settlements of Kampala, the largest urban centre and capital city of Uganda. Kampala's population is estimated at 1.5 million, 27.5% of whom are aged between 15-24 years (28). The city has five metropolitan administrative divisions -Nakawa, Rubaga, Makindye, Central and Kawempe, and is home to Uganda's national referral hospitals, including Mulago national specialized hospital, Kiruddu hospital, Kawempe hospital and Butabika national mental referral hospital.

Sampling
The sample size was calculated using the Kish Leslie formula for cross-sectional studies (29). Since there was limited evidence on the prevalence of Hepatitis B screening or completion of the Hepatitis B vaccination schedule among young psychoactive substance users in informal settlements, we chose a conservative prevalence of 50% (30), a 95% level of confidence, a margin of error (d) of 0.05 and a design effect of 2.0 (30, 31) was used to determine the sample size. This yielded a sample size of 768 young psychoactive substance users. A total of 12 informal settlements were purposively selected for geographical representation of the informal settlements in the city. The settlements included Kinawataka; Luzira; Luzira-Kirombe; Kitintale, Nalukolongo; Wankulukuku-Kabowa; Kamwokya; Bwaise; Katanga; Katwe-Kinyoro; Namuwongo-Soweto and Kyebando.
After the purposive selection of informal settlements, respondent driven sampling was used in the selection of study participants. For each of the informal settlements, we used community leaders who had participated in a previous study in the informal settlements to identify four individuals who acted as primary seeds (32). At the time of enrolment of primary seeds, research assistants made sure that the selected individuals were not under the influence of psychoactive substances. The selected seeds were first interviewed by research assistants prior to being given coupons to enroll secondary seeds.
The secondary seeds were then requested by the primary seeds to report at an agreed venue to be interviewed after providing informed consent. The detailed procedure of undertaking respondent driven sampling is documented by (31).

Eligibility criteria
Only young psychoactive substance users aged 18 years and above were interviewed. These must have stayed in the informal settlement for at least 6 months. All young psychoactive substance users who were sick or under the influence of psychoactive substances were not interviewed.

Variable measurement
The main outcomes of interest in this study were having undergone hepatitis B screening in the last 12 months and completion of the Hepatitis B vaccination schedule based on the WHO recommendation of 3 vaccine doses (33). However, the completion was irrespective of the timing of the vaccinations. Self-reports were used to measure completion of the vaccination schedule.
The independent variables included the respondents' socio-demographic characteristics such as sex, age, history of substance use, level of education, and their knowledge and attitude towards Hepatitis B prevention strategies. Knowledge was assessed using questions on the recommended Hepatitis B vaccine dose and the duration the vaccine protects someone against the Hepatitis B infection.
Attitude was measured using a question on the perceived efficacy of Hepatitis B vaccine. History of substance use was classified as "ever used' which referred to lifetime use of a psychoactive substance; 'recent use' which referred to having used a psychoactive substance in the last 12 months and 'current use' referring to the use of a psychoactive substance in the last 30 days.

Data management and analysis
A structured questionnaire was designed using the kobo tool box online platform and later preloaded onto the kobo collect mobile application. The data collection tools were designed with skips to reduce errors by research assistants. Prior to data collection, all research assistants received training on the study protocol and data collection. All study tools were translated into the local language and thereafter pretested. Data were collected using smart phones and tablets, and later uploaded to an online server at; https://kobo.humanitarianresponse.info. Upon submission, the data were reviewed on a daily basis by the principal investigators as a means of ensuring quality control. Prior to data analysis, data were downloaded in a Microsoft Excel format and further cleaned to reduce any possible errors. Measures of central tendency such as means, median and mode were particularly used to identify errors in the continuous variables. Inferential statistics were used to determine the factors associated with Hepatitis B screening, and completion of the Hepatitis B vaccination schedule. Modified Poisson regression analysis was used to determine the factors associated with Hepatitis B screening since the prevalence of screening for Hepatitis B was greater than 10% (34,35). Bivariate analysis was done first to establish the association between predictor variables and screening for Hepatitis B. A cut off p-value of less than 0.2 was set for variables eligible to be included in the multivariable model (36). Prevalence ratios (PR) and their corresponding 95% confidence intervals were used as the measure of risk.
Given that the prevalence of completion of the Hepatitis B vaccination schedule was a rare occurrence (less than 10%) among young psychoactive substance users, we used logistic regression to determine the predictors. Initially, bivariate logistic regression was used to determine the predictors of completion of the hepatitis B vaccination schedule. Predictors that had a p-value of less than 0.2 were included in the multivariable model. Odds Ratios (OR) were used as the appropriate measure of risk.

Characteristics of respondents
A total of 768 participants were enrolled (response rate of 100%). The mean age (SD) of respondents were 21.5±2.1 years. More than three quarters (78.5%) of respondents were male, 39.2% were Catholic, 78.9% had never married, and 64.6% reported earning less than USD 68.0 per month (Table   1).
Psychoactive substance use among young people in informal settlements Figure 1 shows the distribution of psychoactive substance use among respondents. About 74%, 54.3% and 52% were current users of alcohol, khat and marijuana respectively. In addition, 9.2% and 1.7% were current users of kuba and heroin.
Hepatitis B screening and associated factors among young psychoactive substance users in Kampala's informal settlements Only13.3% reported ever being screened for HBV infection, among those 5.9% reported to have tested positive. Two percent reported having suffered from Hepatitis B in the last 12 months (figure 2).  Factors associated with completion of the hepatitis B vaccination schedule among young psychoactive substance users in informal settlements Table 3  vaccination schedule among young psychoactive substance users who felt the vaccine was effective in preventing hepatitis B were 11.8 times higher compared to those who felt it was not effective (aOR 11.8, 95% CI: 1.13-110.14, p=0.039).

Discussion
Among young psychoactive substance users living in urban informal settlements, we found low levels of HBV screening, HBV vaccination uptake, and low rates of completion of the vaccination schedule.
These findings are significant, given the current strategy of HBV micro-elimination by 2030 (37). The strategy recommends the need to scaleup hepatitis B prevention strategies to all underserved populations such as those residing in informal settlements. Screening for HBV infection is recommended for high-risk groups especially those with a prevalence of ≥ 2 (3). However, only 13.3% of the young psychoactive substance users in this study had ever screened for hepatitis B despite a prevalence of 2.0%. This is mainly attributed to the lack of awareness on HBV infection. Low awareness about HBV and its prevention has recently reported in other key populations in Uganda (38). Besides, available data indicate that informal settlements in Kampala are characterized by limited access to health care services (39), which could also have affected screening rates. In some areas especially urban settings, access to screening and vaccination services comes at a cost. This study showed that young psychoactive substance users with a higher level of income were more likely to screen for hepatitis B compared to those who had a lower level of income. This could be attributed to the high cost of accessing hepatitis B prevention services (43). In some situations, health facilities providing these services are located further away from informal settlements. Therefore, young psychoactive substance users in informal settings incur transport costs to access hepatitis B prevention services. A lack of the financial resources therefore reduces the chances of low-income earners screening for HBV.
Completion of the hepatitis B vaccination schedule was also low, due to insufficient knowledge about the vaccine and HBV infection, and the fact that a significant proportion of young psychoactive substance users did not know where to access the vaccine. Limited access to health services has also been documented as a barrier to uptake of hepatitis B prevention services (13). Our findings are also similar to a study among young injection drug users in the US where only 10% of younger participants reported having completed the hepatitis B vaccine series (44).
Young psychoactive substance users who had competed the hepatitis B vaccination schedule were more likely to have been screened. Usually, hepatitis B screening precedes vaccination in most healthcare facilities thus higher screening rates. Young psychoactive substance users who felt that the vaccine was effective in preventing hepatitis B viral infection were more likely to have screened for hepatitis B. This is so because positive attitude has been shown to positively impact the uptake of Young psychoactive substance users who had ever screened for hepatitis B were more likely to have completed the schedule than those who had never screened. Having screened for hepatitis B is an indicator of a better health seeking behaviour. In addition, those who had ever screened may have felt to be at an elevated risk of the HBV and therefore, undertaking the vaccination would protect them against the infection. Young psychoactive substance users who felt the vaccine was effective were more likely to have completed the vaccination schedule compared to those who did not. This reechoes the fact that a positive attitude is more likely to positively impact preventive behaviours such as vaccination. Such individuals always believe in the protective efficacy of the vaccine, and are bound to complete the vaccination schedule at all costs.
The strength of this study is that it provides useful insights into the predictors of screening and hepatitis B vaccination status of young psychoactive substance users in informal settlements, an area that is less studied. However, there are some limitations. This study relied on self-reports that may be liable to social desirability bias for substance use and testing results. The crossectional design cannot establish causation between hepatitis B screening rates and completion of the hepatitis B vaccination schedule. In addition, these results cannot be generalised to all young people living in informal settlements.

Conclusion And Recommendations
This study indicates that both Hepatitis B screening and vaccination schedule completion rates are low among young psychoactive substance users. Generally, lack of knowledge and negative attitude towards the Hepatitis B vaccine were strong predictors of hepatitis B screening and completion of the Research Ethics Committee (MakSPH HDREC). Given the sensitivity of the study population, permission to interview the study participants was also sought from the local authorities and from peer leaders within the communities where data was collected. Written informed consent was also sought from all study participants prior to participating in the study.

Consent for publication: Not applicable Availability of data and materials
The datasets analysed during the current study are available from the corresponding author on reasonable request.

Competing interests
The authors declare that they have no competing interests     Figure 1 History of psychoactive substance use among young people in Kampala's informal settlements Figure 2 Hepatitis B testing and vaccination among young psychoactive substance users in Kampala's informal settlements Reasons young psychoactive substance users gave for not being vaccinated against hepatitis B (Multiple responses)