Pre-cART Elevation of CRP and CD4+ T-Cell Immune Activation
The random subcohort was not statistically different from the parent cohort by baseline demographics, clinical status, and laboratory results, except for a slightly lower baseline creatinine clearance although all participants had CrCl ≥60 cc/min (CrCl <60 cc/min was an exclusion criterion for the parent study). The case–cohort had a median age [interquartile range (IQR)] of 35 years (29–40) and was composed of 215 (45%) women and 231 (49%) black, 146 (31%) Asian, and 48 (9%) white individuals (Table 1). The median BMI (IQR) was 21.8 kg/m (19.6–24.4), with 97 (21%) overweight or obese and 58 (12%) undernourished or underweight participants. On enrollment, the median CD4 T-cell count (IQR) was 167 cells per cubic millimeter (79–219), and the median plasma HIV RNA level (IQR) was 5.11 log10 copies per milliliter (4.60–5.53). TB coinfection was common (24%), and the prevalence of hepatitis B virus coinfection was 5%.
In the parent trial of 1571, 236 (15%) participants were cases who developed the composite primary outcome of WHO stage 3 or 4 diagnosis or death by 96 weeks after cART initiation. The most frequent incident events were TB (27.1%), death (16.9%), cytopenia (15.7%), serious bacterial infection (11.4%), and weight loss (10.6%) (see Supplemental Digital Content Figure 1, http://links.lww.com/QAI/A696). Notably, cases from Haiti, India, and Thailand were disproportionately more likely to experience weight loss than cases from other countries and TB was one of the top 3 incident diagnoses among cases from all countries, except the United States (data not shown). Cases differed from controls by race, country, BMI, and baseline CD4 T-cell count (P < 0.01), and cases were more likely to have a history of past or current TB (P = 0.001) (Table 1).
All available blood, plasma, and PBMC samples were used to quantify biomarkers. Notably, some of the blood and plasma samples from India could not be exported, and participants from Thailand and India did not have archived PBMC samples. Compared with participants lacking PBMC samples, those with available samples for T-cell activation measurement had similar baseline age, gender, BMI, hemoglobin, and CD4 T-cell count but a significantly lower baseline median HIV RNA level (4.99 vs. 5.18 log10 copies/mL, P = 0.04). Table 2 shows the median pre-cART biomarker values grouped by quartile in the random subcohort and by study group in the full case–cohort. Except for CRP and IP-10, pre-cART biomarker values did not differ significantly between cases and controls. Compared with controls, cases had significantly higher median concentrations of CRP (6.3 vs. 3.03 mg/mL, P = 0.02) and IP-10 (2079.11 vs. 1203.81 pg/mL, P = 0.001). Individual pre-cART immune activation biomarkers were associated with a number of baseline study population characteristics. Notably, except for CRP (P = 0.10) and CD8 T-cell activation (P = 0.11; data not shown), biomarkers varied significantly by country (P < 0.001; see Supplemental Digital Content Figure 2, http://links.lww.com/QAI/A696).
Cox-proportional hazards models stratified for country and treatment group were used to estimate the hazards of the primary outcome (incident WHO stage 3 or 4 disease or death within 96 weeks after cART initiation), for each pre-cART biomarker level grouped by quartile relative to the lowest quartile. In univariate analysis, elevated baseline levels of several biomarkers (highest quartile relative to lowest quartile) were associated with clinical progression after cART initiation, including sCD14 [hazard ratio (HR), 2.20; 95% CI: 1.01 to 4.79], IP-10 (HR, 2.81; 95% CI: 1.27 to 6.24), CRP (HR, 2.19; 95% CI: 1.11 to 4.34), CD4/DR+/CD38 (HR, 4.39; 95% CI: 1.22 to 15.69), and CD8/DR+/CD38 (HR, 6.32; 95% CI: 1.50 to 26.67) (Table 3). In multivariate analyses adjusting for baseline sex, age, BMI, CD4 T-cell count, and hemoglobin, only highest quartile CRP [adjusted hazard ratio (aHR), 2.53; 95% CI: 1.02 to 6.28] and CD4/DR+/CD38 T-cell activation (aHR, 5.18; 95% CI: 1.09 to 24.47) remained associated with the primary outcome, compared with the first quartile of both markers (Table 3 and Supplemental Digital Content Figure 3, http://links.lww.com/QAI/A696). The highest quartile of sCD14 showed a trend toward an association with clinical progression (aHR, 2.24; 95% CI: 0.96 to 5.21), as did the highest quartile of CD8/DR+/CD38 T-cell activation (aHR, 4.28; 95% CI: 0.88 to 20.76). Adjustment for baseline HIV RNA level did not substantially alter the models (Table 3 footnote). To account for the high pre-cART TB prevalence, separate multivariate models were developed that adjusted for TB at study entry and showed similar findings: there was a trend toward association that does not reach statistical significance for the highest quartile CRP (aHR, 2.43; 95% CI: 0.98 to 6.04; P = 0.06) and clinical progression, whereas CD4/DR+/CD38 T-cell activation maintained its association with clinical progression (aHR, 5.56; 95% CI: 1.04 to 29.76; P = 0.045) (see Supplemental Digital Content Table, http://links.lww.com/QAI/A696). In addition, when we set a strict definition of incident TB as occurring >4 weeks after entry to avoid misclassifying persons with subclinical prevalent TB as having incident TB, we still note that persons with the highest quartile CRP values at baseline have an increased HR of 1.63 (P < 0.05) of developing a WHO stage 3 or 4 outcome.
We explored ROC curve analysis to assess the predictive power of pre-cART CRP concentration as a marker for clinical HIV progression post-cART initiation (ie, incident WHO stage 3 or 4 disease or death by 96 weeks on cART). Highest quartile CRP concentration (>10 mg/L) had a specificity of 77% but low sensitivity (40%). Lowering the cutoff to CRP concentration >5 mg/L had the best predictive power but overall low sensitivity (55%) and specificity (62%). In unadjusted ROC curve analysis, the area under the curve (AUC) for CRP greater than 5 mg/L was 0.60. After adjusting for baseline age, sex, country, BMI, hemoglobin, CD4 T-cell count, plasma HIV RNA, and baseline TB, the area under the curve was 0.71, irrespective of the cutoff used (CRP >5 mg/L or CRP >10 mg/L; Fig. 2), indicating that CRP levels pre-cART might have fair discriminating power to distinguish HIV-infected persons who are likely to clinically progress after cART initiation from persons who are unlikely to progress.
(Enlarge Image)
Figure 2.
Pre-cART CRP as a prediction tool for clinical failure. ROC analysis was performed to evaluate if elevated levels of CRP pre-cART can be used to predict clinical failure post-cART initiation. The CRP cutoff was varied using observed CRP levels. After adjusting for baseline age, sex, country, BMI, hemoglobin, CD4 T-cell count, plasma HIV RNA, and baseline TB, the area under the curve (AUC) was 0.71, irrespective of the cutoff used (CRP >5' mg/L or CRP >10 mg/L).
Results
Baseline Characteristics
The random subcohort was not statistically different from the parent cohort by baseline demographics, clinical status, and laboratory results, except for a slightly lower baseline creatinine clearance although all participants had CrCl ≥60 cc/min (CrCl <60 cc/min was an exclusion criterion for the parent study). The case–cohort had a median age [interquartile range (IQR)] of 35 years (29–40) and was composed of 215 (45%) women and 231 (49%) black, 146 (31%) Asian, and 48 (9%) white individuals (Table 1). The median BMI (IQR) was 21.8 kg/m (19.6–24.4), with 97 (21%) overweight or obese and 58 (12%) undernourished or underweight participants. On enrollment, the median CD4 T-cell count (IQR) was 167 cells per cubic millimeter (79–219), and the median plasma HIV RNA level (IQR) was 5.11 log10 copies per milliliter (4.60–5.53). TB coinfection was common (24%), and the prevalence of hepatitis B virus coinfection was 5%.
In the parent trial of 1571, 236 (15%) participants were cases who developed the composite primary outcome of WHO stage 3 or 4 diagnosis or death by 96 weeks after cART initiation. The most frequent incident events were TB (27.1%), death (16.9%), cytopenia (15.7%), serious bacterial infection (11.4%), and weight loss (10.6%) (see Supplemental Digital Content Figure 1, http://links.lww.com/QAI/A696). Notably, cases from Haiti, India, and Thailand were disproportionately more likely to experience weight loss than cases from other countries and TB was one of the top 3 incident diagnoses among cases from all countries, except the United States (data not shown). Cases differed from controls by race, country, BMI, and baseline CD4 T-cell count (P < 0.01), and cases were more likely to have a history of past or current TB (P = 0.001) (Table 1).
Pre-cART Immune Activation
All available blood, plasma, and PBMC samples were used to quantify biomarkers. Notably, some of the blood and plasma samples from India could not be exported, and participants from Thailand and India did not have archived PBMC samples. Compared with participants lacking PBMC samples, those with available samples for T-cell activation measurement had similar baseline age, gender, BMI, hemoglobin, and CD4 T-cell count but a significantly lower baseline median HIV RNA level (4.99 vs. 5.18 log10 copies/mL, P = 0.04). Table 2 shows the median pre-cART biomarker values grouped by quartile in the random subcohort and by study group in the full case–cohort. Except for CRP and IP-10, pre-cART biomarker values did not differ significantly between cases and controls. Compared with controls, cases had significantly higher median concentrations of CRP (6.3 vs. 3.03 mg/mL, P = 0.02) and IP-10 (2079.11 vs. 1203.81 pg/mL, P = 0.001). Individual pre-cART immune activation biomarkers were associated with a number of baseline study population characteristics. Notably, except for CRP (P = 0.10) and CD8 T-cell activation (P = 0.11; data not shown), biomarkers varied significantly by country (P < 0.001; see Supplemental Digital Content Figure 2, http://links.lww.com/QAI/A696).
Predictors of HIV Clinical Progression on cART
Cox-proportional hazards models stratified for country and treatment group were used to estimate the hazards of the primary outcome (incident WHO stage 3 or 4 disease or death within 96 weeks after cART initiation), for each pre-cART biomarker level grouped by quartile relative to the lowest quartile. In univariate analysis, elevated baseline levels of several biomarkers (highest quartile relative to lowest quartile) were associated with clinical progression after cART initiation, including sCD14 [hazard ratio (HR), 2.20; 95% CI: 1.01 to 4.79], IP-10 (HR, 2.81; 95% CI: 1.27 to 6.24), CRP (HR, 2.19; 95% CI: 1.11 to 4.34), CD4/DR+/CD38 (HR, 4.39; 95% CI: 1.22 to 15.69), and CD8/DR+/CD38 (HR, 6.32; 95% CI: 1.50 to 26.67) (Table 3). In multivariate analyses adjusting for baseline sex, age, BMI, CD4 T-cell count, and hemoglobin, only highest quartile CRP [adjusted hazard ratio (aHR), 2.53; 95% CI: 1.02 to 6.28] and CD4/DR+/CD38 T-cell activation (aHR, 5.18; 95% CI: 1.09 to 24.47) remained associated with the primary outcome, compared with the first quartile of both markers (Table 3 and Supplemental Digital Content Figure 3, http://links.lww.com/QAI/A696). The highest quartile of sCD14 showed a trend toward an association with clinical progression (aHR, 2.24; 95% CI: 0.96 to 5.21), as did the highest quartile of CD8/DR+/CD38 T-cell activation (aHR, 4.28; 95% CI: 0.88 to 20.76). Adjustment for baseline HIV RNA level did not substantially alter the models (Table 3 footnote). To account for the high pre-cART TB prevalence, separate multivariate models were developed that adjusted for TB at study entry and showed similar findings: there was a trend toward association that does not reach statistical significance for the highest quartile CRP (aHR, 2.43; 95% CI: 0.98 to 6.04; P = 0.06) and clinical progression, whereas CD4/DR+/CD38 T-cell activation maintained its association with clinical progression (aHR, 5.56; 95% CI: 1.04 to 29.76; P = 0.045) (see Supplemental Digital Content Table, http://links.lww.com/QAI/A696). In addition, when we set a strict definition of incident TB as occurring >4 weeks after entry to avoid misclassifying persons with subclinical prevalent TB as having incident TB, we still note that persons with the highest quartile CRP values at baseline have an increased HR of 1.63 (P < 0.05) of developing a WHO stage 3 or 4 outcome.
We explored ROC curve analysis to assess the predictive power of pre-cART CRP concentration as a marker for clinical HIV progression post-cART initiation (ie, incident WHO stage 3 or 4 disease or death by 96 weeks on cART). Highest quartile CRP concentration (>10 mg/L) had a specificity of 77% but low sensitivity (40%). Lowering the cutoff to CRP concentration >5 mg/L had the best predictive power but overall low sensitivity (55%) and specificity (62%). In unadjusted ROC curve analysis, the area under the curve (AUC) for CRP greater than 5 mg/L was 0.60. After adjusting for baseline age, sex, country, BMI, hemoglobin, CD4 T-cell count, plasma HIV RNA, and baseline TB, the area under the curve was 0.71, irrespective of the cutoff used (CRP >5 mg/L or CRP >10 mg/L; Fig. 2), indicating that CRP levels pre-cART might have fair discriminating power to distinguish HIV-infected persons who are likely to clinically progress after cART initiation from persons who are unlikely to progress.
(Enlarge Image)
Figure 2.
Pre-cART CRP as a prediction tool for clinical failure. ROC analysis was performed to evaluate if elevated levels of CRP pre-cART can be used to predict clinical failure post-cART initiation. The CRP cutoff was varied using observed CRP levels. After adjusting for baseline age, sex, country, BMI, hemoglobin, CD4 T-cell count, plasma HIV RNA, and baseline TB, the area under the curve (AUC) was 0.71, irrespective of the cutoff used (CRP >5' mg/L or CRP >10 mg/L).
SHARE
