Determinants of self-reported correct knowledge about tuberculosis transmission among men and women in Malawi: evidence from a nationwide household survey

The current study used data taken from the 2015–16 Malawi Demographic and Health Survey (MDHS). The 2015–16 MDHS sample was selected using a two-stage cluster sampling design and produced a nationally representative sample. The census sampling frame is considered as a complete list of all the census standard enumeration areas (SEAs). Thus, in the first stage, 850 SEAs (i.e., 173 SEAs in urban areas and 677 SEAs in rural areas) were selected with probability proportional to the SEA size. During the second stage, a fixed number of 30 and 33 households per urban rural cluster/SEA, respectively, were selected with an equal probability systematic selection criterion. All women and men of reproductive age 15–49 years and 15–54 years respectively, who were either permanent residence of the selected households or visitors who stayed in the household the night prior to the data collection were eligible for the interviews. The MDHS selected a total of 27,516 households, of which 24,562 women and 7478 men were successfully interviewed for the response rate of 97.7 and 94.6% respectively. Using women’s and men’s questionnaires, data were collected on socio-demographic characteristics and major health indicators, including knowledge, attitudes, and behaviors related to other health issues such as injections, smoking, fistula, tuberculosis HIV/ acquired immune deficiency syndrome (AIDS), and non-communicable diseases (NCDs). One of the key aims of The DHS Program is to collect data that are comparable across countries. Thus, to achieve this, standard model questionnaires have been developed and these model questionnaires—which have been reviewed and modified in each of the eight phases of The DHS program—form the basis for the questionnaires that are implemented in each country. The datasets for women and men were explored and after excluding respondents with missing data, a total of 28,862 respondents (6937 men and 21,925 women) were included in our analysis.

We conducted our analyses while taking into account the complex design of the survey (i.e. weighting, clustering, and stratification). First, the baseline statistics were presented as frequency and weighted percentage. Second, the bivariate analyses using Chi-Square test were performed to explore the distribution of the selected characteristics according to the correct knowledge about the mode of TB transmission among adult women and men. Third, using the generalized estimating equation (GEE) logistic regression, the multivariable analyses were performed to investigate the strength of associations between the selected factors and correct knowledge about TB transmission. GEE models were used to account for the correlated responses within the hierarchical data such DHS data [37, 38]. Variables were selected for analysis based on their importance in literature [39]. We further selected variables that were significant (p < 0.25) in the Chi-Square test for adjustment in the GEE multivariable analyses so as to avoid large type II errors. Both unadjusted and adjusted odds ratios (aORs) and 95% confidence intervals (CIs) with their p-values were presented. P-values < 0.05 were considered as statistically significant. All analyses were performed using SAS software for Windows, version 9.4 (SAS Institute, Cary, NC, USA).

The 2015–2016 MDHS was implemented by the National Statistical Office (NSO) and the Community Health Sciences Unit (CHSU). The protocols and procedures that were developed for data collection were reviewed and approved by the ICF Macro Institutional Review Board (ICF Macro IRB) and the Malawi National Health Science Research Committee. The MDHS 2015–2016 complied with all requirements of the US Department of Health and Human Services’ the 45 Code of Federal Regulations 46 (45 CFR 46), Protection of Human Subjects [40]. Before this study was conducted, the authors sought permission from the MEASURE DHS for use of the data beyond the primary purpose by which data were collected. At the beginning of each interview, informed consent (both written and oral consent) was obtained from all eligible participants. Furthermore, a parent or guardian provided consent prior to the participation by a child or anybody below the age of 18 years [40]. Overall, data obtained from respondents under the DHS program is anonymous as names are of the participants are not written down thus ethics approval for this study was not required.

A total of 28,862 adults (6937 males and 21,925 females) were sampled and analyzed in this study. Table 1 presents the baseline characteristics of the study participants stratified by sex. The overall prevalence of correct about TB knowledge in the general population of Malawi was adequate (61.5%). Most of the respondents (40.6%) were distributed in the age group 15 to 24 years and near two-thirds (59.2%) of the respondents had primary school education. Nearly 30.0% of respondents were residing in the richest households while about two-thirds (64.3%) currently in union. Approximately 40% of the participants did not have any form of mass media and a similar proportion (38.6%) of respondents were employed in agriculture sectors. Furthermore, over three-fourth (77.4%) of participants were rural dwellers and 44.98% were southern region dwellers.

Table 2 presents the domains that were used to measure correct knowledge about the mode of TB transmission among women and men of reproductive age. Ninety-seven percent of men and 94% of women had heard of TB. Overall, 8908 (71.83%) of the participants responded correctly that TB is spread from one person to another through air by coughing or sneezing. Furthermore, 81.34% of respondents believed that TB can be cured and 31.89% of participants would want a family member’s TB status kept secret. There were significant differences between men and women who reported having heard of TB, such that 69.64% of women and 78.77% of men reported that TB is spread through the air by coughing or sneezing (P < .0001). Additionally, 85.44% of women and 80.05% of men believe that TB can be cured (P < .0001) while 25.39% of men and 33.94% of women would want a family member’s TB status kept secret (P < .0001). Figure 1 shows the distribution of the domain that were used to construct knowledge related to TB transmission.

Table 3 shows the prevalence of correct knowledge about TB transmission among men and women of reproductive age by sociodemographic characteristics. The prevalence of correct knowledge about TB transmission was significant different from those who had incorrect knowledge by sex of the respondents (P < .0001), age of the respondents (P < .0001), educational level (P < .0001), household wealth (P < .0001), religion (P < .0001), amount of media exposure (P < .0001), respondent’s occupation (P < .0001), respondents with a belief that TB can be cured (P < .0001), respondents would want a family member’s TB status kept secret (P < .0001), place of residence (P < .0001), geographical region (P < .0001), and ethnicity (P < .0001).

Table 4 shows results of univariate and multivariate logistics regression that were used to test independent predictors of the given variables and assess their strength of associations between those predictors with correct knowledge about TB transmission. In univariate analysis characteristics that were significantly associated with correct knowledge about TB transmission included sex of the respondents, age of the respondents, educational level, household wealth, religion, amount of media exposure, occupation, tuberculosis can be cured, TB status kept secret, place of residence, geographical region, and ethnicity (all P-values less than 0.05). The results of multivariate logistics regression showed that respondents of age groups 25–34 years odds (adjusted odds ratio [aOR]: 1.219; 95% confidence interval [CI]: 1.145–1.297; P < .0001), 35–44 years (aOR: 1.275; 95% CI: 1.187–1.371; P < .0001), and 45+ years (aOR: 1.239; 95% CI: 1.116–1.375; P < .0001) had increased compared to those respondents of age group 15 to 24 years. The odds of having correct knowledge about TB transmission was also high in respondents with primary education (aOR: 1.253; 95% CI: 1.144–1.371; P < .0001) and secondary and high education (aOR: 2.000; 95% CI: 1.793–2.232; P < .0001) compared to those with no formal education. Furthermore, respondents from middle household wealth (aOR: 1.106; 95% CI: 1.016–1.205; P- = 0.0205), richer households (aOR: 1.096; 95% CI: 1.005–1.196; P = 0.0387), and richest households (aOR: 1.166; 95% CI: 1.053–1.292; P = 0.032) had increased odds of having correct knowledge about TB transmission compared to respondents from poorest households. Additionally, respondents who had exposure to 3 forms of mass media (aOR: 1.190; 95% CI: 1.076–1.315; P = 0.0007), respondents who believed that TB can be cured (aOR: 1.708; 95% CI: 1.600–1.823; P < .0001), respondents from urban (aOR: 1.165; 95% CI: 1.063–1.277; P = 0.0011), and respondents from Lomwe tribe (aOR: 1.286; 95% CI: 1.066–1.551; P = 0.0086) had also increased odds of having correct knowledge about TB transmission. Conversely, agricultural employee (aOR: 0.909; 95% CI: 0.843–0.981; P = 0.0143), respondents who would want a family member’s TB status to be kept secret (aOR: 0.886; 95% CI: 0839–0.935; P < .0001) had reduced odds of having correct knowledge about TB transmission. Furthermore, respondents from central region (aOR: 0.896; 95% CI: 0.819–0.980; P = 0.0161) and northern region (aOR: 0.581; 95% CI: 0.512–0.659; P < .0001), had also reduced odds of having correct knowledge about TB transmission compared to those from the southern region.

This study cannot determine the causation between the exposure variables and the outcome variable due to the cross-sectional nature of the study design. Considering that the sample size of females was 3 times that of male participants, and that a large percentage of the participants were under the age of 25, the external validity of the results to the entire Malawian population maybe compromised (i.e., the results may not be generalizable to the Malawian population). Nevertheless, the factors observed in this study may help inform TB control programs aimed at improving overall TB knowledge in Malawi. However, despite these limitations, the findings presented in this study would contribute to our understanding of the determinants of TB transmission which may improve the quality of TB management in Malawi. These results can be generalized only in a certain specific population such as women and those age less than 25 years.