Gender differences in correlations of self-reported marijuana use with a creatinine-normalized urine biomarker among persons with HIV

BackgroundCannabis use is common among persons with HIV (PWH). However, accurately quantifying cannabis consumption and its components such as THC has been a long-standing challenge due to the variety of cannabis products available, variability in smoking and other consumption behaviors, as well as the reliability and validity of self-reported cannabis measures. Further, there is a paucity of research on the relationship between a timeline follow back (TLFB) and cannabis metabolites/biomarkers in older, underrepresented populations of PWH. We sought to determine the association between the self-reported quantity of cannabis used with the creatinine-normalized urine biomarker (THC-COOH) primarily among exclusive flower users and as a secondary analysis among cannabis users of any method of administration. We also explored whether the associated effect size differed by gender at birth. MethodData were collected from 2018-2022 from participants in the MAPLE study, a longitudinal study examining health effects of cannabis among PWH in Florida. This analysis included data from 253 PWH (mean age 49, 41% Female, 16% White, 68% Black, and 13% Hispanic) who used cannabis products. The quantity of daily cannabis use over the past 30 days was collected by trained interviewers at three time points (baseline, 1 year and 2 years follow-ups) using a self-reported, calendar-based TLFB. Using these findings, cannabis quantity was summarized in terms of mg of THC per day and urine THC-COOH, a biomarker for THC, was determined by mass spectroscopy from 103 participants. A linear mixed effect model was used to test the association between the creatinine-normalized THC-COOH levels and average quantity of mg THC consumed per day for exclusive marijuana flower users and also for all users of any marijuana product. We also stratified by gender to investigate the effect size in males and females. ResultsAmong the exclusive marijuana flower users we found an association between mg of THC per day and THC-COOH urine biomarkers, overall and in both males and females. The strength of the fixed effect was stronger in females than males. However, when we examined users of any marijuana product, not just flower, we did not find a significant association between mg of THC per day and THC-COOH urine biomarkers among males or females. ConclusionsTLFB is a valid instrument to measure self-reported marijuana flower use. However, the fixed effect between self-reported consumption of cannabis with urine THC-COOH biomarkers is stronger in females than in males.