Table 4.
Agreement between ARV resistance profiles reported by participants testing three TAQAS. The panel identifier and the number of participants (n) are shown at the top of the table. The interpretation system is given as “various” when participants used different interpretation systems or “Stanford” for the subgroup of participants that used the Stanford Database. Interpretation of resistance was considered to agree when all, or all but one participant agreed, and results were excluded for boosted or combinations of drugs, when samples did not contain drug resistance mutations (DRMs), and where disparities resulted from the participants’ failure to detect DRM(s). The level of agreement is indicated as the proportion of panel samples where participants agreed on the ARV resistance interpretation as a fraction of the number of samples tested.
| ARV drugs | Interpretation systems used (level of agreement (%)) |
|||||
|---|---|---|---|---|---|---|
| TAQAS 1 (n = 10) Various | TAQAS 1 (n = 5) Stanford | TAQAS 2 (n= 12) Various | TAQAS 2 (n = 6) Stanford | TAQAS 3 (n = 12) Various | TAQAS 3 (n = 9) Stanford | |
| Amprenavir | 2/3 | 3/3 | 2/3 | 3/3 | 2/3 | 2/3 |
| Indinavir | 2/3 | 3/3 | 2/3 | 3/3 | 2/3 | 2/3 |
| Nelfinavir | 2/3 | 3/3 | 3/3 | 3/3 | 2/3 | 2/3 |
| Ritonavir | 2/3 | 3/3 | 3/3 | 3/3 | 2/3 | 2/3 |
| Saquinavir | 2/3 | 3/3 | 2/3 | 3/3 | 2/3 | 2/3 |
| Lopinavir | 2/3 | 3/3 | 0/3 | 1/3 | 2/3 | 2/3 |
| Atazanavir | 2/3 | 3/3 | 2/3 | 3/3 | 1/3 | 2/3 |
| Abacavir | 2/2 | 2/2 | 3/3 | 3/3 | 2/3 | 3/3 |
| Lamivudine | 2/2 | 2/2 | 3/3 | 3/3 | 3/3 | 3/3 |
| Stavudine | 2/2 | 2/2 | 0/3 | 3/3 | 3/3 | 3/3 |
| Zidovudine | 1/2 | 1/2 | 1/3 | 3/3 | 3/3 | 3/3 |
| Tenofovir | 0/2 | 2/2 | 2/3 | 3/3 | 3/3 | 3/3 |
| Efavirenz | 2/2 | 2/2 | 1/3 | 3/3 | 2/3 | 3/3 |
| Nevirapine | 2/2 | 2/2 | 3/3 | 3/3 | 3/3 | 3/3 |
| Total (%) | 25/35 (71)a | 34/35 (97)a | 27/42 (64)a | 40/42 (95)a | 31/42 (74) | 35/42 (83) |
Level of inter-laboratory agreement when participants used various systems was lower than when all participants used the Stanford Database in TAQAS 1 and 2 (p < 0.01).