Study setting and period

The study was conducted from May 7, 2021, to June 21, 2021, in Horro Guduru Wollega Zone, Oromia Region. The zone is divided into 11 woredas (districts) and one administrative town. Its capital, Shambu town, is 315 kilometres from Ethiopia’s capital, Addis Ababa. The zone has fifty (50) health centres and three (3) hospitals. In each health facility, a TB clinic has been established with at least one TB focal healthcare provider to regularly manage cases and follow their treatment. Fifty (50) health centres and three (3) hospitals in the district provided TB care, including directly observed therapy short course (DOTS), during the study period. During initiation phase anti-TB drug are administrated directly under observation of healthcare provider or TB focal person whereas, in the continuation phase patients receive their anti-TB drugs from the health facilities on every week and manage their pills by themselves.

Study design and population

A facility-based cross-sectional study design was employed from May 7, 2021, to June 21, 2021. The source population included all adult TB patients taking anti-TB treatment in Horro Guduru Wollega Zone public health centres, while study population included a randomly selected TB patient whose age was ≥ 18 years old taking anti-TB treatment during the study period. TB patients who were 18 years and above, came to TB clinic during the study period were included in the study. However, TB patients who cannot properly communicate, were mentally ill, had physical disabilities, and pregnant or lactating mothers were excluded from the study.

Sample size determination and sampling procedure

The sample size was calculated using the single population formula (n = Z^α ₂ ²p (1–p)/d²) under the following assumptions: Z score at 95% confidence interval CI = 1.96, margin of error = 5 P = 38.9%, the prevalence of under nutrition among TB patients in Shashemane town, central Ethiopia^{(Reference Hussien, Hussen and Seid15)} giving a sample size of 365. By considering the design effect of 1.5, it gave 547. Since the number of TB patients who have follow up at a public health centre in the study area was less than 10,000 (N = 798) we used a correction formula which yields a sample size of 324. Adding a 5% no-response rate, the final sample size became 341.

All public health centres in the study area were considered for this study. First, we choose all eleven (11), woredas, and one (1) town administration, by taking into account facilities with a high TB patient flow. Then, two (2) health centres from each woreda were randomly selected. Therefore, a total of 23 health centres were included in the study. Before the beginning the data collection the list of the study participants were obtained from TB registration log book of respective health centres and used as a sampling frame. The required numbers of participants who will be selected from each health centre were determined based on proportion to population size allocation. Finally, study participants were selected using a computer-generated simple random sampling technique from TB registration available in the TB clinic.

Data collection tools and techniques

Questionnaires: The structured questionnaires which are adopted from previous studies.^{(Reference Ayele14,Reference Bekalu and Fikirte17,Reference Admassu20)} was employed. Primary data was collected using a structured questionnaire, which included background information, household income, participants’ and/or household food insecurity status, dietary diversity scores, and lifestyle behaviours. Household food security status was assessed using the Household Food Insecurity Access Scale (HFIAS), and dietary diversity scores were assessed using a food frequency questionnaire which was then converted into dietary diversity tertiles by computing for the groups.

Weight: Weight was measured using a regularly calibrated beam balance. Clients were instructed to remove shoes and heavy clothing. Participants stood straight and unassisted in the centre of the weighing scale platform. Weight was measured to the nearest 0.1 kg. The validity of the scale was checked by using an object of known weight every morning and between the measurements.

Height: Height was measured with a stadiometer, which was readily available and routinely used in the TB clinic. The participants were instructed to take off their shoes and stand erect, looking straight in a vertical plane, feet together, and knees straight. The five contact points (heels, calves, buttocks, shoulder blades, and the back of the head) were designed to make contact with the stadiometer’s wall. The height was measured to the nearest 0.1 cm (centimetre). Before starting the measurement, the stadiometer was checked using calibration rods.^{(Reference Shukla, Pandey and Singh21)}

All anthropometric measurements were taken in triplicate, and the average results were used in subsequent analyses. Anthropometrics were standardised in order to reduce inter observer error. The body mass index (BMI) was calculated as the weight in kg divided by the height in metres squared (kg/m²).

The questionnaire was prepared in English first, then translated into Afan Oromo, and finally back to English to ensure consistency by a bilingual expert. Data were collected by six (6) trained health professionals who had prior knowledge of TB and worked in TB clinics. Two BSc nurses were assigned as supervisors to monitor the data collection process.

The data quality was ensured by carefully designing, translating, and pretesting questionnaires. Before data collection, the questionnaires were pretested on a 5% sample size in an area other than the actual data collection area. Unclear or ambiguous questions were modified, and incorrect skip patterns were corrected. Two days of training were provided for data collectors and supervisors by the principal investigator on data collection tools, data collection techniques, approach to the interviews, and maintaining the privacy and confidentiality of the respondents. Every day following data collection, the questionnaires were reviewed and checked for completeness by the supervisors and the principal investigator. The scale pointer was checked to be zero before taking each measurement.

Operational definitions

Severe chronic energy deficiency: In this study, refers to study participants whose BMI < 15.5 for males and < 20.6 kg/m² for females.

Mild to moderate chronic energy deficiency: 15.5–18.2 for males and 20.6–21.8 kg/m² for females.

Normal nutritional status: 18.3–21.5 for males and 21.9–23.0 kg/m² for females.

Overweight: 21.6–22.2 for males and 23.1–24.5 kg/m² for females

Obese: above 22.2 kg/m² for males and > 24.5 kg/m² for females.^{(Reference Sinaga, Worku and Yemane22)}

Nutritional care and support: It has many components which includes the provision of water, hygiene and food safety service or food aid by any organisation. It was measured by dichotomous yes or no questions, participants who get at least a service in one of the components in the last four weeks were considered as those who have nutrition care and support.^{(Reference Dargie, Tesfaye and Worku23)}

Household food security: It was measured by using the HFIAS measurement tool, which consists of nine (9) item occurrence questions that represent a generally increasing level of severity of food insecurity (access), and each item has three frequency of occurrence questions asked to determine whether the condition occurred rarely (once or twice), sometimes (three to ten times), or frequently (more than ten times) in the previous four weeks. Each frequency question weighs from 1 to 3 points, giving a total score of 27. Based on the responses given to the nine questions and the frequency of their occurrence over the past 30 d, participants were assigned a score that ranged from 0 to 27. Finally, an index was dichotomised into ‘food-insecure households’ for scores greater than one and ‘food-secure households’ for scores zero and one.^{(Reference Ayiraveetil, Sarkar and Chinnakali24–26)} According to the HFIAS score, there are three categories of food insecurity: mildly food-insecure (if Q1a = 2 or Q1a = 3 or Q2a = 2 or Q2a = 3 or Q3a = 1 or Q4a = 1), moderately food-insecure (if Q3a = 2 or Q3a = 3 or Q4a = 3 or Q5a = 1 or Q5a = 2 or Q6a = 1 or Q6a = 2), severely food-insecure (if Q5a = 3 or Q6a = 3 or Q7a = 1 or Q7a = 2 or Q7a = 3 or Q8a = 1 or Q8a = 2 or Q8a = 3 or Q9a = 1 orQ9a = 2 or Q9a = 3).^{(26,Reference Coates, Swindale and Bilinsky27)}

Food Frequency Questionnaire: Participants were asked about the usual frequency of consumption of each of the 22 food items they have consumed over the last month last three months. Participants were asked to report the frequency of consumption of each food per day, per week or per month using the past 1 month as a reference. The food frequency questionnaire was calculated using the product sum method. The average frequency of food intake per week and month of the food frequency questionnaire was converted to a daily frequency value. Consumer definitions were done and computed for nine groups of foods. The participants were coded as a ‘consumers’ of a food item if they had consumed the food item at least once per week^{(Reference Regassa, Endris and Habtemariam28)}

Dietary diversity score: The total count of food groups that an individual consumed based on the DDS guideline of nine food groups was measured by using food frequency questionnaires that consisted of 22 food items. These food items were grouped in to 9 (nine), then their sum product were ranked in to tertiles as low dietary diversity score = <3 food groups, medium dietary diversity = 4 and 5 food groups, and high dietary diversity = > 6 food groups.⁽²⁶⁾

Cigarette smokers: Participants who had been smoking cigarettes for more than 6 months and smoked a minimum of one packet of cigarettes per week.⁽²⁹⁾

Problem with eating: A patient who has at least one of the problems (mouth ulcer, nausea and/ or vomiting, poor appetite, or pain or difficulty of swallowing).

Intensive phase: The first two months of period by which anti-TB drugs is given every day under the direct observation of the healthcare provider, with the aim of rapidly reducing the number of mycobacterium tuberculosis present in the patient’s body and minimising the risk of transmission.^{(Reference Wulandari and Karolina30)}

Continuation Phase: The period ranges from 4 to 6 months by which anti-TB drug is given with aim of killing the remaining mycobacterium tuberculosis from the previous stage to prevent recurrence.^{(Reference Wulandari and Karolina30)}

Data processing and analysis

Data were visually checked and entered into EpiData version 4.6 and then exported to SPSS version 26 software package (manufactured by IBM®) for analysis. Descriptive analysis was carried out to describe study participants using figures and tables.

The dependent variable was the patient’s nutritional status, which was categorised into normal, undernutrition, and overnutrition based on body mass index. The sociodemographic characteristics, general health and nutrition-related factors, household food security status, and dietary diversity score were the independent variables. A bivariable multinomial logistic regression model was performed to select candidate variables for multinomial logistic regression analysis to identify independent predictors of nutritional status. Variables having a P-value of 0.25 in the bivariable analysis were then included in the multivariable multinomial logistic regression model. Variables with a P-value of < 0.05 in the multivariable multinomial logistic regression analysis were considered independent predictors of nutritional status.

Multicollinearity among independent variables was checked by considering the standard error and tolerance. A risk of multicollinearity among the independent variables was defined as a standard error greater than 2 and a variance inflation factor (VIF) greater than 10. For the finally fitted multivariable logistic regression model, the adequacy of the model to predict the outcome variables was checked by the Hosmer–Lemeshow goodness-of-fit test (P = 0.341).

Ethical approval

This study was conducted according to the guidelines laid down in the Declaration of Helsinki, and all procedures were approved by the ethical review board of Jimma University’s Institute of Health Science (Ref. No. IHR47/2021). Informed written consent was obtained from all subjects/patients.