Between 1999 and November 2009, we recorded 686 deaths in 18 077 individuals aged 15–59 years during 76 989 person-years of observation, with a crude death rate of 8.9 deaths per 1000 person-years (95% CI 8.3–9.6; ). Among the 18 077 individuals, 1333 (7.4%) were known to be HIV-positive, including 476 who seroconverted during the period of observation. Of the 65 674 person-years of observation in persons of known HIV status, 4446 person-years (6.8%) were contributed by HIV-positive individuals.
Number of individuals, observed deaths, person-years of follow-up and crude death rates
shows survival probability between the ages of 15–60 years for the entire population, by sex, in the 5 years before ART became available and in the 5-year period after the introduction of ART in 2004. Before 2004, the probability of dying from any cause between the ages of 15 and 60 years was 51% for men (95% CI = 45–57) and 44% for women (95% CI = 39–49). During 2004–2009, it reduced to 38% (95% CI = 33–44) for men and 32% (95% CI = 28–37) for women. Mortality was significantly lower in 2005–2009 (ART period 2) than in the 5 years before ART introduction (in men, age-adjusted RR = 0.60, 95% CI = 0.47–0.76; in women, age-adjusted RR = 0.57, 95% CI = 0.44–0.71; ). Furthermore, there was a non-significant reduction in mortality in the first year after ART became available (ART period 1; in men, age-adjusted RR = 0.84, 95% CI = 0.58–1.20; in women, age-adjusted RR = 0.81, 95% CI = 0.57–1.15; ). In contrast, among individuals aged 60 years and older, overall mortality did not change (age- and sex-adjusted RR = 1.01, 95% CI = 0.76–1.36 in ART period 1 compared with pre-ART and RR = 1.00, 95% CI = 0.84–1.20 in ART period 2; data not shown).
Kaplan–Meier survival function for the entire study population in the 5 years before (1999–2003) and after (2004–2009) antiretroviral therapy introduction, by sex.
All-cause mortality in adults aged 15–59 years, pre- and post-ART roll-out*
Among the 325 individuals of known HIV status who died in the 5-year period before ART introduction, 216 (66.4%) were HIV infected. Mortality rates by HIV status are shown in and . In the 5 years before ART became available, mortality (deaths per 1000 person-years) was 4.0 (95% CI = 3.3–4.8) among HIV-negative individuals and 116.4 (95% CI = 101.9–133.0) among HIV-positive individuals. During this period, the estimated population-attributable fraction (PAF) of HIV in adults aged 15–59 years was 64%. In the year after ART was introduced (ART period 1), the mortality rate (deaths per 1000 person-years) among HIV-negative individuals was not significantly different (adjusted RR = 0.95, CI = 0.61–1.47) but had shrunk by 25% to 87.4 (adjusted RR = 0.75, CI = 0.53–1.06) among HIV-positive adults. In the period 2005–2009 (ART period 2), mortality among HIV-negative individuals did not change significantly (adjusted RR = 0.93, CI = 0.71–1.21); however, among HIV-positive individuals, it fell further to 39.9 deaths per 1000 person-years (adjusted RR = 0.33, CI = 0.26–0.43). During the 5-year period after ART introduction (2004–2009), the estimated PAF of HIV had dropped to 45%. Among HIV-negative individuals, there was no evidence of a difference in mortality trends between age groups or between men and women (test for interaction P = 0.55 and P = 0.96, respectively). Among HIV-positive individuals, in the year after ART introduction, the reduction in mortality was greatest among those aged 45–59 years; thereafter, the impact was greatest among individuals aged 30–44 years (P = 0.14, test for interaction). There was no evidence of a difference in mortality trends between men and women (P = 0.76, test for interaction).
Mortality rates by sex and age-group, in the 5 years before antiretroviral therapy (ART) introduction and after ART roll-out in 2004, among HIV-positive (top) and HIV-negative (bottom) adults aged 15–59 years.
All-cause mortality in adults aged 15–59 years from 1999 to 2009, pre- and post-ART roll-out*, by HIV status
There was a 27-fold increased mortality risk in HIV-positive compared with HIV-negative individuals aged 15–59 before ART introduction, which fell after ART introduction to 21-fold in the first year (ART period 1; adjusted RR = 21.5, 95% CI = 12.9–36.0) and ninefold in the subsequent 4 years (ART period 2; adjusted RR 9.4, 95% CI = 7.0–12.5) (). The trends of falling mortality risk after ART introduction were similar in each age group ().
Comparison of mortality rates by HIV status in adults aged 15–59 years, pre- and post-ART roll-out, by age group