A Comparative Study of Self-Report, Urinalysis and Hair Analysis in the Detection of Methamphetamine in Yaba Users
Anongphan Junkuy MS*, Apinun Aramrattana MD, PhD**, Pongruk Sribanditmongkol MD, PhD*
Affiliation : * Department of Forensic Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand ** Department of Family Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Background : Three diagnostic methods have dominated drug-abuse research: self-report, urinalysis and hair analysis.
Previous studies have compared detection rates for various drugs, but none has focused a three-pronged concordance study
on the use of methamphetamine (MA).
Objective : To determine and compare the rates of MA detection in urine and hair of subjects who reported consuming MA
in the form of Yaba.
Material and Method: Self-reports of Yaba use, as well as biological specimens for chemical analyses, were collected from
paid volunteers participating in a larger project studying risk-taking behavior of young adults in northern Thailand. All
subjects in the present study reported using Yaba within 90 days of enrollment. Hair analysis for MA followed a validated
protocol that coupled solid phase microextraction (SPME) with gas chromatography-mass spectrometry (GC-MS).
Preliminary urinalysis was by means of REMEDi-HS. Positive urine was confirmed for MA by the SPME/GC-MS protocol.
Results : The MA detection rate by hair analysis (34.3%, n = 172) was significantly higher than by urinalysis (19.1%,
n = 96) (p<0.01; McNemar’s test). All subjects with MA-positive urine samples reported using Yaba within 30 days of
testing, while hair analysis gave positive results for self-reports up to 90 days. Urinalysis showed greater concordance with
self-report than hair analysis if testing occurred within seven days of most recent admitted Yaba use. The reverse was true
after 14 days. Agreement of laboratory findings with self-reports increased if test results for the two biological matrices
were combined. There was no strong agreement between hair analysis and urinalysis for subjects reporting most recent use
within 30 days of testing (kappa = 0.131; 95% CI = 0.022-0.240).
Conclusion : For the Yaba users in the present study, urinalysis for MA significantly detected more positives than hair
analysis if the most recent use reportedly occurred within seven days of testing. Hair analysis yielded better results after
an interval of 14 days, with its window of detection extending up to three months. There were no urine positive samples for
reported use after 30 days. Combining urinalysis and hair analysis increased the probability of detecting recent MA use.
Both urinalysis and hair analysis significantly under-detected MA in the biological samples collected. The combined detection
rate was 44.4%. This discrepancy might have resulted from over-reporting of Yaba use due to social/psychological factors
and/or insufficient MA consumption causing test results to fall below cutoff levels.
Keywords : Yaba abuse, Methamphetamine (MA), Hair analysis, Self-report, Under-detection, Over-report
