Table 3

Modification of the effect of chemsex at baseline on time to first STI diagnosis among pre-exposure prophylaxis (PrEP) users by age, education or income

No chemsex reportedChemsex reportedHR (95% CI) for chemsex within strata
nHRnHR
Effect modification by age
 18–357501.57 (1.17 to 2.10)2902.69 (1.96 to 3.68)1.71 (1.36 to 2.15)
 36–505751.30 (0.97 to 1.74)1641.00 (0.67 to 1.48)0.77 (0.55 to 1.07)
 >502541.00 (ref.)
531.53 (0.90 to 2.60)
1.53 (0.90 to 2.60)
Effect modification by education
 Secondary or under2301.00 (ref.)871.61 (0.98 to 2.64)1.61 (0.98 to 2.64)
 Post-secondary13491.16 (0.81 to 1.65)4201.47 (1.03 to 2.11)1.27 (1.04 to 1.55)
Effect modification by income ($C)
 ≤35 0004491.00 (ref.)1621.71 (1.23 to 2.36)1.71 (1.23 to 2.36)
 35 00175 0006681.01 (0.76 to 1.34)2381.26 (0.92 to 1.71)1.25 (0.96 to 1.63)
 >75 0004621.18 (0.88 to 1.57)1071.24 (0.82 to 1.86)1.05 (0.72 to 1.54)
  • Created by the authors.

  • Models adjusted for age, education, income, PrEP regimen at baseline and year of entry into the cohort (all categorical).

  • For education and income, the group size n in each cell is the average group size from the imputed datasets.