Study setting
The study was conducted in the Jimma zone, Oromia Regional State which is located at a distance of 354 km away from Addis Ababa to the Southwest part of Ethiopia. According to the data from the Jimma Zone Statistical Department in 2017, the zone has an estimated 3,174,484 total population. It has 21 districts with a total of 555 villages. In the zone, there is a branch of national blood transfusion service agency providing blood donation services to the hospitals.
Study design and period
A cross-sectional study was conducted in Jimma Zone among volunteer blood donors who visited the blood bank and blood collection sites for donating blood during study period, have lived in the zone for the last six months and were qualified for blood donation according WHO blood bank guidelines for blood donation eligibility criteria’s (8). Blood donors who refused to give informed consent were excluded. Data were collected from March 10 to April 20, 2018.
Study variables
Dependent variable: HBV infection status
The independent variables were;
Socio-demographic factors: Age, sex, marital status, educational status, residency, occupation
Behavior related factors: Razor and sharp material sharing, unprotected multiple sexual activities, tattooing, ear/nose piercing, using unsafe therapeutic drug injection, number of blood donation
Knowledge related factors: Knowledge about the causative agent, means of transmission, sign and symptoms and treatment of HBV
Treatment-related/clinical factors: Blood transfusion, surgical procedure, dental procedure, HB vaccination status, previous history of hospitalization
Sample size determination
The sample size was calculated manually using a single population proportion formula by taking the prevalence of HBV among blood donors in the Southwest Ethiopia 3.05% (24), 1.5% margin of error and 95% confidence interval (CI). Assuming a 10% non-response rate, the final sample was 555. The prevalence of HBV among blood donors gives the largest sample size than factors associated with it and so used to determine the final sample size.
Sampling techniques
All volunteer blood donors were selected consecutively from the collection sites in Jimma zone and blood bank center during the study period until the required sample obtained. Sampling procedure follows the movement plans of blood bank service due to the data collectors assigned with each team of blood bank staff. Three functional teams established to collect blood from volunteer blood donors. Each team planned to collect 250 blood units within ten days at blood bank center and fifteen days outreach since the number of volunteers in each planned collection site usually unknown. So, the sample size was equally distributed for case teams. After community mobilization, the data collectors moved for blood collection to the planned collection sites with blood bank staffs.
Data collection tool and techniques
Data were collected by a structured questionnaire adapted from previous different literature (8, 24) and it was numbered to identify those who had to respond and/or not. The questionnaire was originally prepared in English and translated into the local language, Afan Oromo and Amharic, for fieldwork purposes and back to English for checking language consistency.
After donors agreed to take part in the study, he or she signed a consent form and data collectors collect baseline information of each participant. Then, the blood sample was taken from blood bags of donated blood to sterile test tubes which further used for the screening with a closed system. Then the collected blood was centrifuged, plasma separated and stored at 2 to 8°C until it was tested. Samples were brought to room temperature before testing. The plasma sample was performed and analyzed for HBsAg using the 4th generation Enzyme-Linked Immune Sorbent Assay (ELISA) test kit by a senior laboratory professional in the blood bank.
Data quality assurance
Data collectors were selected based on the ability to speak the local language and two days orientation was given by the investigators on the objective, process of data collection and field ethics. The whole data collections were supervised by the investigators.
Each questionnaire was cross-checked daily by the investigators for completeness and consistency. ELISA kits were checked for appropriate storage conditions and its expiry date. Internal positive and negative controls were included in each assay run and standard operation procedures and manufacturer instructions were strictly followed.
A pretest was conducted in a nearby zone taking 5% of the total sample to test the data collection tool. Consequently, clarifications and corrections were made on problems encountered about the questionnaire.
Data analysis
Each questionnaire was coded and checked manually for completeness, consistency, and clarity. Then, the coded and cleaned data were entered into Epidata 3.1 and exported to SPSS version 20.0 where statistical analyses were done. Descriptive analyses were done to determine the prevalence of HBV. Bivariate analysis was done to select candidate variables with P < 0.25. Then entered into multivariable analysis to identify independent predictor variables and control for confounders. Finally independent variables at P < 0.05 level of significance with Adjusted Odds Ratio (AOR) and its 95% Confidence Interval (CI) in multivariable logistic regression were used to identify statistical significance.
Operational definition
Knowledge about HBV prevention and control was measured using 18 questions that include general awareness about HBV, mode of transmission, sign and symptoms, complications and treatment based on the current literature. Each correct answer scored 1 and wrong answer or “I don’t know” scored 0. Thus the knowledge score was scaled from 0 to 18. A person scoring a total of 9 or less was taken as having poor knowledge and those scoring 10 and above had good knowledge.