Modelling survival and factors associated with HIV-infected and -uninfected patients of prostate cancer at the University Teaching Hospital, Lusaka, Zambia

Abstract

Background Prostate cancer continues to have a high incidence and fatality rate over the world, especially among those infected with the Human Immunodeficiency Virus (HIV), with higher mortality in Africa than on other continents. Zambia has one of the highest anticipated prostate cancer death rates, despite modest progress and a little higher than normal prevalence of prostate cancer. As a result, this study examined the survival rates of HIV-infected and HIV-uninfected prostate cancer patients, as well as the variables that influence mortality. Methods We used data from the cancer disease hospital (CDH) in Lusaka, Zambia, to perform a 5-year retrospective cohort analysis of prostate cancer registry data. The data was analysed using a Weibull hazard model at multivariate analysis after doing multiple imputation to deal with missing information in the data. Patients were followed up using mobile phone calls to estimate the contribution of their patients' time from the moment of diagnosis to death or the conclusion of the research period. Those who were lost to follow-up were censored at the date of their last known hospital follow-up. Results 662 cases were evaluated. The total amount of time at risk was 7548 months. 290 (43.8%) deaths suggest a death rate of 430 people per 10,000 people per year. The average length of survival was 16 months. In an adjusted model, the following variables had a statistically significant impact on the hazard of death: one year increase in age, increased the hazard of death by about 3%, AHR 1.03 (95% CI: 1.02, 1.05, p= 0.001); HIV positive had reduced hazard of death by about 41%, AHR 0.59 (95% CI: 0.44, 0.79, p= 0.001); Gleason scoreless or equal to eight, the patients with Gleason score greater than eight had increased hazard of death by about 43%, AHR 1.43 (95% CI: 1.27, 1.59, p= 0.001); those on hormonal therapy had reduced hazard of death by about 28% AHR 0.72 (95% CI: 0.54, 0.94, p= 0.018); and those presented with tumour stage one and two had reduced hazard of death by about 82%, AHR 0.18 (95% CI: 0.04, 0.78), p= 0.021). Conclusion Survival from death after learning whether a patient was HIV positive or negative was higher in HIV positives than in HIV negatives, which could be related to HIV negatives having higher Gleason scores than HIV positives who are regularly seen by clinicians for screening. Prostate cancer screening must be advocated for, especially among HIV negative patients, as evidenced by the increased hazard of death compared to HIV positives.