Evaluation of the treatment failure ratio in individuals receiving methadone maintenance therapy via the network scale up method

Background: The network scale up (NSU) method is an indirect size estimation method that has received remarkable attention in estimating the sensitive behaviors. Using methadone maintenance therapy (MMT), which is a treatment for opioid use disorder, is a sensitive topic in many societies. The aim of this manuscript was to estimate the number of MMT users and its failure ratio using the NSU method in the city of Kerman, Iran, in 2016.

Methods: In this cross-sectional study, 1275 men and 1275 women which were aged >18 years and who had lived in the city of Kerman for at least 5 years were recruited via multistage sampling. Data was collected via face-to-face interviews using a questionnaire that was included questions for estimating the network size of the residents of Kerman as well as the number of MMT users and the existing failure among them.

Results: In total, the average network size of the citizens of Kerman was 235; among them, 97 were men and 138 were women. Overall, the numbers of MMT users and failures were estimated at about 5289 and 2731, respectively, leading to a failure ratio about 52%. The treatment failure ratio in the women and men was equal to 55% and 51%, respectively. Among the men, the failure ratio in all age groups was equal to ˜50%. Among the women, the failure ratio in those who were aged <18 years was equal to 76%.

Conclusion: The considerable failure ratio indicates the need for conducting studies on MMT services in order to understand the reasons which exist regarding this failure. This is of particular importance in specific groups, such as in young women. Further, the comparable results with other direct methods indicate that the NSU method could be used in the size estimation of MMT failure ratios.