Chemical analyses of antimalarial medicines purchased using three approaches (convenience-mystery clients, full island-wide survey-mystery clients and randomised-overt sampling) on Bioko Island, Equatorial Guinea; n=677
| Outlets (n) | Acceptable Quality AD and PD | Substandard | Degraded | Falsified | Total |
| Convenience survey using mystery client (samples=31; total brands=12; brands per outlet=0.8) | |||||
| Pharmacies (10) | 16 (76.2%) | 1 (4.8%) | 0 | 4 (19.0%) | 21 |
| Medicine vendors (6) | 9 (90.0%) | 0 | 0 | 1 (10.0%) | 10 |
| Private clinics (0) | 0 | 0 | 0 | 0 | 0 |
| All outlets (16) | 25 (80.7%)* | 1 (3.2%) | 0 | 5 (16.1%)*** | 31 |
| Full island-wide survey using mystery client (samples=368; total brands=60; brands per outlet=0.3) | |||||
| Pharmacies (108) | 236 (91.1%) | 2 (0.8%) | 0 | 21 (8.1%) | 259 |
| Medicine vendors (33) | 50 (92.6%) | 0 | 0 | 4 (7.4%) | 54 |
| Private clinics (33) | 52 (94.5%) | 0 | 0 | 3 (5.5%) | 55 |
| All outlets (174) | 338 (91.9%)* | 2 (0.5%)** | 0 | 28 (7.6%) | 368 |
| Randomised-overt survey(samples=278; total brands=64; brands per outlet=0.7) | |||||
| Pharmacies (62) | 213 (90.2%) | 7 (3.0%) | 0 | 16 (6.8%) | 236 |
| Medicine vendors (14) | 8 (100.0%) | 0 | 0 | 0 | 8 |
| Private clinics (12) | 32 (94.2%) | 1 (2.9%) | 0 | 1 (2.9%) | 34 |
| All outlets (88) | 253 (91.0%) | 8 (2.9%)** | 0 | 17 (6.1%)*** | 278 |
Significant difference between sampling approaches for each quality category was as follows:
*p=0.037: between convenience survey using mystery clients and full island-wide survey using mystery clients for acceptable quality (AD and PD) samples.
**p=0.017: between full island-wide survey using mystery clients and randomised-overt survey for substandard samples.
***p=0.040: between convenience survey using mystery clients and randomised-overt survey for falsified samples.
Other comparisons were not significantly different (p>0.050).
Acceptable quality: 85%–115% SAPIs for both AD and PD.
Substandard: <85% or >115% SAPI of either AD or PD or both.
Degraded: <85% SAPI plus products of degradation of either/both AD or PD or both.
Falsified: zero SAPI for both AD and PD and visible differences (mistakes) on the packaging.
ACA, artemisinin-containing antimalarial; AD, artemisinin derivative (always the ACA); PD, partner drug (always the non-ACA); SAPI, stated active pharmaceutical ingredient.