Are we missing the importance of missing values in HIV prevention Randomized clinical trials? A Literature review

Objective: Missing data in HIV prevention trials is a common complication. Even small amounts of missing values in randomized trials can cause bias, inefficiency and loss of power. We examined the extent in which HIV prevention literature manages missing data. Methods: We used a database maintained by the HIV/AIDS Prevention Research Synthesis (PRS) Project at the Centers for Disease control and Prevention (CDC) to identify relevant trials. The PRS cumulative database was searched on June 15, 2010 and all citations that met the following criteria were retrieved: All Randomized control trials (RCT) which reported HIV/STD/HBV/HCV behavioral interventions with a biological outcome from 2005 to present. Results: Out of the 57 studies identified, all had some level of missing values. We found that the average missing values per study ranged between 3% to 97%. Averaging over all studies the percent of missing values was 26%. None of the studies reported the missing data assumptions used in their RCTs. We expect only 12% of studies to report unbiased results. Conclusions: There is a need for more detailed and thoughtful consideration of the missing data problem in HIV prevention trials. In the current state of managing missing data we risk major biases in interpretations.