We conducted unmatched community-based case control study with one to two ratios.
The study participants were selected by simple random method using the line list. We used
structured questionnaire to collect data from cases and controls. The data cleaning and filling was one on Epi infoVer.7.2. The collected data was analyzed by SPSS and presented in figure, table and graph. Variables in bivariable model at p-value ≤ 0.20 were entered to multivariable model; variables at p-value ≤ 0.05 were identified as significant risk factors.
