Subgroup analysis of factors associated with MTC proportion in PrEP trials
| Variable | Subgroup | Study (n) | MTC proportion (95% CI) | I2 (%) | Meta-regression coefficient | SE | p Value |
| Age (years) | <30 | 4 | 34.9% (27.6% to 43.1%) | 64.50 | Ref | ||
| ≥30 | 4 | 69.6% (56.1% to 80.4%) | 87.70 | 1.42 | 0.32 | <0.001 | |
| Gender | Women | 3 | 31.3% (27.0% to 36.0%) | 0 | Ref | ||
| Men | 2 | 71.7% (31.2% to 93.4%) | 94.60 | 1.71 | 0.57 | 0.0023 | |
| Both | 5 | 71.0% (58.7% to 80.9%) | 92.30 | 1.66 | 0.43 | 0.0001 | |
| Population | High-risk women | 3 | 31.3% (27.0% to 36.0%) | 0 | Ref | ||
| PWID | 1 | 67.4% (59.2% to 74.7%) | – | 1.49 | 0.76 | 0.0494 | |
| Sexually active heterosexual adults | 1 | 79.7% (68.6% to 87.6%) | – | 2.13 | 0.79 | 0.0073 | |
| MSM and transgender | 2 | 71.7% (31.2% to 93.4%) | 94.60 | 1.71 | 0.62 | 0.0059 | |
| Serodiscordant couples | 3 | 69.2% (49.2% to 83.8%) | 95.50 | 1.58 | 0.53 | 0.0032 | |
| Transmission mode | Vaginal | 3 | 31.3% (27.0% to 36.0%) | 0 | Ref | ||
| Needles/syringe | 1 | 67.4% (59.2% to 74.7%) | – | 1.49 | 0.72 | 0.0382 | |
| Vaginal/penile | 4 | 71.9% (56.6% to 83.3%) | 93.30 | 1.70 | 1.70 | 0.0004 | |
| Rectal | 2 | 71.7% (31.2% to 93.4%) | 94.60 | 1.71 | 0.59 | 0.0038 | |
| Medication intensity | Daily | 9 | 56.1% (38.6% to 72.3%) | 97.30 | Ref | ||
| Intermittent | 1 | 85.8% (78.1% to 91.1%) | 1.56 | 1.16 | 0.1806 | ||
| Drug type | TDF | 3 | 55.3% (30.0% to 78.2%) | 96.40 | Ref | ||
| FTC/TDF | 7 | 61.8% (39.7% to 79.9%) | 97.40 | 0.27 | 0.79 | 0.7333 | |
| Sample size | <1500 | 2 | 83.3% (76.5% to 88.4%) | 13.70 | Ref | ||
| ≥1500 | 8 | 52.8% (34.2% to 70.7%) | 97.60 | −1.47 | 0.87 | 0.0887 | |
| Follow-up months | ≤24 | 2 | 65.2% (15.9% to 94.9%) | 97.80 | Ref | ||
| ≤36 | 6 | 52.9% (29.8% to 74.8%) | 98.10 | −0.50 | 1.00 | 0.6128 | |
| >36 | 2 | 73.2% (59.4% to 83.6%) | 70.30 | 0.42 | 1.22 | 0.7310 | |
| Clinical trial type | Non-open-label RCT | 7 | 64.0% (49.0% to 76.6%) | 95 | Ref | ||
| Open-label RCT | 3 | 50.1% (19.2% to 81.0%) | 97.50 | −0.58 | 0.65 | 0.3730 | |
| Jadad scale score | <5 | 8 | 59.9% (39.6% to 77.3%) | 97.80 | Ref | ||
| 5 | 2 | 60.6% (44.3% to 74.9%) | 72.70 | −0.01 | 0.91 | 0.9936 |
PWID, people who inject drugs; MSM, men who have sex with men; MTC, medicine-taking compliance; PrEP, pre-exposure prophylaxis; RCT, randomised controlled trial; Ref, reference category; FTC, emtricitabine; TDF, tenofovir disoproxil fumarate.