Table 2.
Regression Coefficients, Odds Ratios and Development of the CSF HIV Risk Scorea in the CHARTER Study Cohort at Study Entry, 2004–2007
| Variable | Regression Coefficient | Odds Ratio | 95% CI | P Value | Shrunkenb Regression Coefficient βi | Reference Value Wij (Midpoint) | βi (Wij-WiRef) | Risk Score (βi × [(Wij-WiRef)]/Bc) |
|---|---|---|---|---|---|---|---|---|
| CPE score | −0.266d | 0.77 | 0.67, 0.88 | <0.001 | −0.249 | |||
| ≥10 | 12 (W1Ref) | 0 | 0 | |||||
| 5–9 | 7 | 1.245 | 6 | |||||
| <5 | 4 | 1.992 | 9 | |||||
| Race | ||||||||
| White | 1.00 | Referent | 0 (W2Ref) | 0 | 0 | |||
| Black | 0.593 | 1.81 | 1.06, 3.09 | 0.02 | 0.556 | 1 | 0.556 | 3 |
| Hispanic/other | 0.875 | 2.39 | 1.16, 4.95 | 0.02 | 0.820 | 1 | 0.820 | 4 |
| Current depression | ||||||||
| No | 1.00 | Referent | 0 (W3Ref) | 0 | 0 | |||
| Yes | 0.808 | 2.25 | 1.18, 4.28 | 0.01 | 0.757 | 1 | 0.757 | 4 |
| HIV medication adherence, % | ||||||||
| ≥95 | 1.00 | Referent | 97.5 (W4Ref) | 0 | 0 | |||
| 85–94 | 0.584 | 1.79 | 0.67, 4.79 | 0.23 | 0.547 | 89.5 | 0.547 | 3 |
| <85 | 0.599 | 1.82 | 0.90, 3.68 | 0.10 | 0.561 | 80.0 | 0.561 | 3 |
| Log plasma RNA, copies/mL | 1.584d | 4.88 | 3.91, 6.09 | <0.001 | 1.486 | |||
| <1.699 | 1.699 (W5Ref) | 0 | 0 | |||||
| 1.699–2.299 | 1.999 | 0.446 | 2 | |||||
| 2.301–3.999 | 3.150 | 2.156 | 10 | |||||
| >4.0 | 5.627 | 3.928 | 18 | |||||
| Current cART, months | −0.011d | 0.99 | 0.98, 1.00 | 0.07 | −0.010 | |||
| ≥36 | 75 (W6Ref) | 0 | 0 | |||||
| 25–35 | 30 | 0.450 | 2 | |||||
| 13–24 | 18 | 0.570 | 3 | |||||
| 7–12 | 9 | 0.660 | 3 | |||||
| ≤6 | 3 | 0.720 | 4 | |||||
Abbreviations: cART, combination antiretroviral therapy; CHARTER, Central Nervous System Human Immunodeficiency Virus Antiretroviral Therapy Effects Research; CI, confidence interval; CNS, central nervous system; CPE, central nervous system penetration effectiveness; CSF, cerebrospinal fluid; HIV, human immunodeficiency virus.
a Under the points system, meaningful categories of predictors were created, and the distance from a chosen reference category was determined in regression units. Integer points were assigned to each level of predictor, and the risk estimate was determined from total points assigned by a reference table (30). Points were rounded to the next integer.
b Regression coefficients were multiplied by a shrinkage factor of 0.937.
c B represents the constant for the point system or the number of regression units that will correspond to 1 point. The constant reflects the risk of detecting CSF HIV RNA associated with the study population's mean duration on cART, 20.6 months (B = 20.6 × 0.011 = 0.227).
d Regression coefficient for continuous form of variable.