Table 1. Sample size calculation for the study on determinants of first-line antiretroviral treatment failure among adult patients on antiretroviral therapy in Mettu Karl Specialized Hospital, South West Ethiopia, 2020.

Variables	The ratio of cases to controls	% of Controls exposed	AOR	% of Cases exposed	Sample size
Baseline BMI< 18.5 kg/m2 [19]	1:3	44.5	2.75	68.8	194(49, 145)
Having history of lost to follow up [20]	1:3	6.01	3.66	19.0	282(71, 211)
Baseline CD4 < 50 cells/ mm3 [21]	1:3	10.1	3.96	30.5	167(42, 125)
Poor adherence [17]	1:3	6.08	2.986	16.2	416(104, 312)
Smoking [22]	1:3	18	5.9	56.4	72 (18, 54)
History of TB co-infection [22]	1:3	26.7	3.9	58.7	110(28, 82)