The validity of drug use responses in a household survey in Puerto Rico: comparison of survey responses with urinalysis.

AIMS: The available evidence suggests that the validity of drug use responses in general population surveys is low. We have conducted a household survey to examine viral infections in the general population of Puerto Rico employing a number of procedures believed to increase the validity of drug use responses, as well as confidentiality and privacy: telling participants of toxicological verification of drug use prior to the interview, ACASI self-interviewing, and interviewing outside households in mobile examination units.

METHODS

The study employed a stratified cluster sample of 1654 adults 21 to 64 years old, 532 recruited while urine samples were being collected and 1122 recruited after urinalysis was discontinued due to budgetary reasons.

RESULTS

Drug use rates calculated from participants recruited while urinalysis was being conducted did not vary significantly to those derived from participants recruited after urinalysis was discontinued. Sensitivity of responses of drug use during the last three days was 80.0% for marihuana, 76.2% for cocaine, and 40.0% for heroin. The lower validity of heroin reports did not seem to be the result of underreporting as it was reported by more individuals than the test detected.

CONCLUSION

We conjecture that the reasonably good validity of the drug use responses might have been the result of the parent study being about a health issue other than drug use, and that interviewing was conducted outside households in mobile units. These findings buttress the value of conducting methodological trials to identify procedures which yield valid responses of drug use.