Background: More than one-fourth of adult HIV patients had malnutrition which have high risk of relapse after treatment. Therefore, assessing the longitudinal episodes and its predictors have great importance.

Objective: to assess longitudinal trends and predictors of under nutrition among HIV positive adults attending Public Hospitals in southwest Ethiopia, 2019.

Methods: Longitudinal study with repeated measure was conducted among 618 randomly selected records of adult HIV clients on treatment. Malnutrition was assessed using the records of weight and height in different point on follow up. (0, 6, 12, 18 and 24 months of ART follow up). Analysis of variance, Analysis covariance and spaghetti plot were done to compare the mean change in BMI across different repeated measures. To assess predictors of malnutrition episode, linear mixed model was conducted considering fixed and random variables. Thus parameter estimate, p-value with 95% Confidence interval was estimated via Maximum likelihood method. From the model information criteria Akaikes information criteria (AIC) was used to assess model fitness with smaller value as indicative of better model fit.

Results: A total of 480 records were reviewed with mean age of 36 years (± 9 years). A total of 354(73.8%) of clients mentioned that they got dietary counseling. While, 34.6% of them got nutritional support. Statistical significant increasing trend of mean BMI score across the five follow up intervals (F statistics = 13.9, p value = 0.0001) were observed. Being male (β = -0.72; P = 0.044), with problem of eating difficulty (β =-1.61; p = 0.0001), having anemia (β = -1.51; p = 0.003), shorter follow up interval (β = 0.04.; p=0.129), not getting nutritional counselling (β = 0.63; p=0.32) and diarrheal disease (β = -0.04; p=0.129) were negatively associated with improvement in BMI indices.

Conclusions: There is improvement in nutritional status after initiation of ART. Presence of eating disorder, anemia, not getting nutritional counseling, short follow interval were significant predictors of nutritional status.

Implications: Health professional working in ART clinic should emphasize for early detection, and treatment of causes of eating disorder, diarrheal disease and others.