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Table 2 Multivariate Cox regression analyses for time to change from first- to second- line combination antiretroviral therapy (cART)

From: Antiretroviral treatment use, co-morbidities and clinical outcomes among Aboriginal participants in the Australian HIV Observational Database (AHOD)

  n (%) changed Time at risk (PY) Rate of change/100PY AHR 95 % CI p-value Overall p
Indigenous        0.957
No 416 (37.1) 4946.7 14.2 1 - -  
Yes 6 (25.0) 112.6 16.0 1.01 0.63-1.63 0.957  
Year of HIV diagnosis        0.662
<1997 148 (27.9) 2429.9 15.8 1 - -  
≥1997 240 (46.5) 2229.0 12.4 0.96 0.80-1.15 0.662  
Missing 34 (35.0) 400.4 15.7 1.15 0.88-1.52 0.300  
Year of starting cART        <0.001
Prior to 2000 104 (18.5) 2634.5 17.4 1 - -  
2000 or later 318 (54.6) 2424.8 10.9 0.54 0.46-0.63 <0.001  
Clinic setting        <0.001#
General practice 157 (44.5) 1965.9 10.0 1 - -  
Hospital outpatient 92 (36.8) 958.1 16.5 1.36 1.10-1.69 0.005  
Sexual Health Clinic 173 (32.0) 2135.3 17.2 1.53 1.28-1.83 <0.001  
Prior mono or dual antiretroviral therapy      0.081
No 354 (41.1) 4012.5 12.6 1 1 -  
Yes 68 (24.0) 1046.8 20.5 1.24 0.97-1.59 0.081  
Hepatitis C antibody positive        0.053
No 389 (37.9) 4600.7 13.9 1 - -  
Yes 33 (28.0) 458.6 18.5 1.25 1.00-1.58 0.053  
Prior AIDS-defining illness        0.304
No 391 (37.4) 4711.4 13.9 1    
Yes 31 (31.3) 348.0 19.5 1.16 0.88-1.52 0.304  
CD4 count at time of commencing cART (per mm3)     0.011*
<200 45 (32.1) 531.0 17.9 1 - -  
200-349 82 (43.9) 808.4 13.0 0.85 0.64-1.13 0.267  
>350 215 (44.7) 2404.0 11.1 0.73 0.57-0.93 0.010  
missing 80 (23.8) 1315.8 19.5 0.96 0.76-1.22 0.746  
HIV viral load at time of commencing cART (copies/ml)     0.200*
≤400 150 (49.3) 1439.0 10.7 1 - -  
400-10000 124 (41.1) 1426.6 12.5 1.09 0.87-1.36 0.436  
>10000 70 (34.0) 897.2 15.2 1.17 0.92-1.48 0.200  
missing 78 (23.5) 1296.5 19.6 1.22 0.60-2.49 0.582  
First-line cART regimen        <0.001#
PI-containing (no NNRTI or II) 104 (23.8) 1535.4 21.7 1 - -  
NNRTI-containing (No PI or II) 290 (47.6) 3185.3 10.0 0.56 0.47-0.65 <0.001  
Other (± NNRTI ± PI ± II) 28 (28.6) 338.6 20.7 1.01 0.78-1.32 0.927  
  1. Indigenous status included a priori in multivariate model; change defined as addition of ≥ 2 new drugs or ≥ 1 new class in regimen, off treatment periods were included in duration of time to change; missing categories not included in calculations of p-values. Factors not associated on univariate analysis (p > 0.1) with shorter time to change from 1st to 2nd line cART were: gender, age at 1st cART, sexual orientation and past/current Hepatitis B infection
  2. PY Person-years, AHR Adjusted hazard ratio, CI Confidence interval, cART combination antiretroviral therapy (at least 3 antiretroviral agents used in combination), PI protease inhibitor, NNRTI Non-nucleoside reverse transcriptase inhibitor, II Integrase inhibitor
  3. * p for trend, # p for heterogeneity