Table 4. CD4 and VL at switch to second-line for first-line failure in patients receiving 12-weekly CD4 count monitoring, but no VL monitoring (LCM).
| Clinical or immunological failure criteria triggering switch | Number switching (%) | Median (IQR) CD4at switch | n≥250 cells/mm3 at switch (%) | n<50 cells/mm3 at switch (%) | n died within 1 year of switch (%) | VL assayed‡ (% of total) | n with VL<400 copies/ml (% of those with VL assayed) | Median VL in those >400 copies/ml | ROC area under the curve for CD4 predicting VL<400 copies/ml |
| Total switched | 361 (100%) | 63 (36–95) | 7 (2%) | 145 (40%) | 23 (6%) | 187 (52%) | 23 (12%) | 86,568 | 0.70‡‡ |
| CD4<100 cells/mm3 | 265† (73%) | 47 (30–71) | 0 | 140 (53%) | 8 (3%) | 122 (46%) | 9 (7%) | 99,784 | 0.64 |
| Other CD4* | 43 (12%) | 113 (92–153) | 3 (7%) | 1** (2%) | 2 (5%) | 29 (67%) | 6 (21%) | 33,340 | 0.67 |
| WHO 4 | 37 (10%) | 116 (83–179) | 3 (8%) | 4 (11%) | 12 (32%) | 23 (62%) | 6 (26%) | 87,536 | 0.64 |
| Multiple WHO 3 | 6 (2%) | 130 (95–241) | 0 | 0 | 1 (17%) | 5 (83%) | 0 (0%) | 59,990 | N/A |
| Single WHO3 | 10 (3%) | 118 (103–165) | 1 (10%) | 0 | 0 (0%) | 8 (80%) | 2 (25%) | 166,858 | 1.00 |
| p = 0.0001 | p<0.0001 | p<0.0001 | p<0.0001 | p = 0.005†† | p = 0.03 | p = 0.08 |
mostly CD4 declines to just over 100 cells/mm3
65/265 (25%) also had WHO 4 events at the time of switch (plus 1 of the 43 switching for other CD4 reasons)
CD4 <50 cells/mm3 on day of switch: did not have any previous CD4 <50 cells/mm3 or 2 previous CD4s <100 cells/mm3
retrospectively on stored plasma
p = 0.95 in a multivariable logistic regression model for VL assayed (yes/no) adjusted for whether switched to second-line before or after 1 Jan 2007 (p = 0.12), whether or not joined second-line studies (p = 0.05), sex (p = 0.89) and age at switch (p = 0.61). More patients switched for other CD4 reasons later in the trial, reflecting wider promotion of other immunological criteria as switch criteria in WHO 2006 guidelines[9]; see Results.
ROC area under the curve = 0.62 (95% CI 0.45–0.79) in 115 patients enrolled in second-line studies, vs 0.78 (95% CI 0.58–0.99) in 72 patients not enrolled in second-line studies.
Note: ROC = receiver operating characteristic, see Figure 2. One switch 34 weeks after ART initiation: all others ≥48 weeks.