Self-report is one of the most widely used techniques for the assessment of illicit drugs. Nonetheless, the data obtained from illicit drugs user through self-reports is associated with bias and random error. Therefore, validation of these kinds of studies should be determined.

The aim of this study was to determine the agreement between family report of amphetamine/methamphetamine abuse by deceased individual and laboratory findings from autopsy.

In this cross-sectional study, demographic, epidemiological and laboratory data of people, whose cause of death was illicit drug use in Iran, between March 2015 and March 2018, were extracted by two checklists. Individuals with both laboratory results and family report regarding the amphetamine/methamphetamine use were extracted and agreement between their results was assessed using the Kappa index, sensitivity, specificity, positive predictive value, negative predictive value, and ROC curve.

The total number of people who died due to illicit drugs use were 7762. There were 3716 (47.8%) cases with both questionnaire responses and lab results; 88.8% were male and the rest were female. Family reports demonstrated moderately low validity with a low Kappa agreement rate 0.33 (95% CI: 0.30, 0.36), sensitivity 60.3% (95% CI: 56.9–63.7) and moderately high specificity 77.9% (95% CI: 76.4–79.4).

Results of this study imply that self-report of family cannot be used as a valid response for amphetamine usage in deceases related to illicit drugs use.