Estimating Cannabis Consumption in Milligrams of THC From Self-Reported Hit Size

Estimating delta-9 tetrahydrocannabinol (mgTHC) using hits involves converting hits to grams via a grams-per-hit ratio (GPHR). Previous studies assumed a single hit size (SHS), ignoring individual hit size variations. This study investigates a multiple qualitative hit size (MQHS) approach based on self-reported hit sizes (small, medium, large) to improve mgTHC estimates.

Adults (N = 1,824) who used cannabis in the past week completed an online survey on cannabis consumption, reporting quantities in hits and grams, and estimating their hit sizes. We calculated mgTHC using both SHS (0.06g/hit for flower, 0.012g/hit for concentrate) and MQHS. For the MQHS approach, we calculated median GPHRs for each hit size group and assigned those medians to individuals within that group.

For flower, median GPHR increased with hit size (small: 0.042, medium: 0.062, large: 0.093). The MQHS estimate for mgTHC from flower was higher than SHS for large hits (95% CI: [12.4, 50.0]) but showed no difference for medium or small hits (95% CI: [-3.2, 8.1]; 95% CI: [-27.6, 3.4]). For concentrate, median GPHR was similar for small and medium hits but lower than large hits (small: 0.024, medium: 0.025, large: 0.035). MQHS estimates for mgTHC were higher than SHS for all hit sizes (95% CI: [46.3, 86.3]; 95% CI: [24.8, 45.5]; 95% CI: [11.5, 36.5] for large, medium, small hits, respectively).

The MQHS estimates captures hit size variability for flower. The floor effect with median GPHRs for concentrates suggests further investigation is needed for MQHS estimates with concentrates. The MQHS approach illustrates a method to develop new standard GPHRs for each qualitative hit size group, after further investigation.