Behavioural and psychosocial characteristics and baseline demographic variables of users of daily oral PrEP (emtricitabine/tenofovir disoproxil), associated with TFV-DP concentrations in linear regression analysis using generalised estimating equations (n=257; total number of DBS samples=461)
| Univariable | Multivariable | |||||
| β* | (95% CI) | P value | β* | (95% CI) | P value | |
| Demographic characteristics | ||||||
| Age (years, modelled as cubic spline; ref.: 21 years) | 0.0040 | 0.0008 | ||||
| 35 | 3.45 | (−273 to 280) | 13.3 | (−271 to 298) | ||
| 50 | 29.3 | (−211 to 270) | 51.6 | (−196 to 299) | ||
| 55 | 139 | (−103 to 382) | 168 | (−80.5 to 417) | ||
| 60 | 288 | (9.48 to 567) | 325 | (44.0 to 606) | ||
| 65 | 457 | (104 to 809) | 501 | (153 to 849) | ||
| Self-declared ethnicity: non-white | −82.2 | (−245 to 80.8) | 0.32 | |||
| Place of residency in the Netherlands: outside Amsterdam | −45.8 | (−171 to 79.2) | 0.47 | |||
| Education level | ||||||
| Low, middle, other | 0 | 0.57 | ||||
| High | −40.5 | (−181 to 100) | ||||
| Employment† | ||||||
| Employed | 0 | 0.33 | ||||
| Unemployed | −65.3 | (−388 to 257) | ||||
| Other (retired, volunteer, disabled, student) | 135 | (−53.0 to 322) | ||||
| Net monthly income in €‡ | ||||||
| ≤1700 | 0 | 0.97 | ||||
| 1701–2950 | 16.6 | (−139 to 172) | ||||
| >2950 | 18.5 | (−149 to 186) | ||||
| Living situation | ||||||
| Alone | 0 | 0.048 | ||||
| With partner | 10.6 | (−116 to 137) | ||||
| With parents/Flatmates | −190 | (−356 to −23.6) | ||||
| Steady relationship§ | −21.5 | (−139 to 96.4) | 0.72 | |||
| Sexual preference: not exclusively homosexual¶ | 155 | (6.71 to 302) | 0.041 | |||
| Sexual behaviour (past 3 months) | ||||||
| Any STI** | −10.7 | (−113 to 91.4) | 0.84 | |||
| Total number of sex partners (log transformed)†† | 51.5 | (−0.158 to 103) | 0.051 | |||
| Total number of condomless anal sex acts with casual partners (log transformed)‡‡ | 35.7 | (−6.15 to 77.6) | 0.095 | |||
| Condomless anal sex with a casual partner (6 months prior to inclusion in AMPrEP) | 175 | (33.0 to 317) | 0.016 | 166 | (36.5 to 296) | 0.012 |
| Mental health characteristics and drug use | ||||||
| Score ≥24 on sexual compulsivity scale†† (indication of sexual compulsivity) | −62.7 | (−189 to 63.3) | 0.33 | |||
| Chemsex§§,‡‡, | −12.9 | (−118 to 92.0) | 0.81 | |||
| MHI-5 score <60††,*** | −67.0 | (−201 to 67.1) | 0.33 | |||
| Score ≥8 on Alcohol Use Disorders Identification Test††† | −85.9 | (−214 to 41.7) | 0.19 | |||
| Score ≥8 on Drug Use Disorder Identification Test‡‡‡ | −29.2 | (−137 to 78.7) | 0.60 | |||
| Neutral to high concern about acquiring HIV§§§ | 104 | (−70.3 to 278) | 0.24 | |||
| Very important to prevent HIV§§§ | 94.0 | (−39.9 to 228) | 0.17 | |||
| Access to mobile application | ||||||
| Extended app | 138 | (15.0 to 261) | 0.028 | 146 | (28.1 to 263) | 0.015 |
| AMPrEP study visit | ||||||
| 24 months vs 12 months | −83.0 | (−146 to −19.6) | 0.010 | −91.5 | (−155 to −28.1) | 0.0047 |
AMPrEP study, Amsterdam, 2015–2018.
*TFV-DP in fmol/punch.
†6 missing.
‡27 missing.
§5 missing.
¶2 missing.
**4 missing.
††14 missing.
‡‡16 missing.
§§Use of γ-hydroxybutyrate, γ-butyrolactone, methamphetamine or mephedrone prior to or during sex in the 3 months prior to inclusion into AMPrEP.
¶¶Indication of an anxiety or depressive mood disorder.
***Indication of an anxiety or depressive mood disorder.
†††Indication of an alcohol use disorder, 15 missing.
‡‡‡Indication of a drug use disorder, 15 missing.
§§§Scale 1–7, dichotomised, at baseline.
AMPrEP, Amsterdam PrEP demonstration project; DBS, dried blood spots; MHI-5, Mental Health Inventory-5; PrEP, pre-exposure prophylaxis; TFV-DP, tenofovir diphosphate .