Association between small airways dysfunction and THC use disorders in the general Swiss population

Small airways dysfunction (SAD) may be associated with Δ⁹-tetrahydrocannabinol (THC), increasing peripheral airway resistance and reactance.

To assess the association between THC use disorders and the presence of spirometry-defined SAD.

The dataset was derived from the Swiss urban cohort CoLaus|PsyCoLaus. SAD was defined by maximal mid-expiratory flow (MMEF) < 65% of predicted value (PV) or MMEF < lower limit of normal (LLN). THC use disorders were defined as the presence of any THC abuse or dependence as assessed using a semi-structured interview. Associations between THC use disorders and SAD were assessed using logistic regression adjusted for age, sex, smoking status and body mass index in model 1. We performed a model 2 adjusted for the same covariables and high blood eosinophils. Association of MMEF with THC use disorders was evaluated using linear regression with the model 1 and 2.

In the baseline cohort (n = 2826), THC use disorders were associated with SAD defined as MMEF<65%PV (OR 2.08, CI95[1.34; 3.24] and MMEF < LLN (OR 2.37, CI95[1.30; 4.33]) and according to the unadjusted model. This association persisted with MMEF<65%PV definition (OR 1.94, CI95[1.21; 3.09] in model 1, OR 1.95 CI95[1.22-3.12] in model 2). In the follow-up cohort (n = 1841), SAD defined as MMEF<65%PV or MMEF < LLN was associated with THC use disorders only in the unadjusted model (OR 1.83, CI95[1.01; 3.32] and OR 3.31, CI95[1.45; 7.56]). THC use disorders were associated with lower MMEF (ml/s and z-score) in the baseline cohort in model 1 and 2.

THC use disorders seemed to be associated with an increased risk of spirometry-defined SAD and lower small airways spirometric value in this population-based cohort, highlighting the need for screening of THC in patients investigated for SAD.