Cox proportional hazard-model application: time to cervical cancer screening among women living with HIV in South Africa

Abstract

There is an increased risk of cervical cancer among women living with HIV. While studies have long examined the association between cervical cancer among women with HIV, no study has examined the time taken for women with HIV to undergo cervical cancer screening as well as the hazard thereof in South Africa. The study used cross-sectional data from the 2016 South Africa Demographic and Health Survey. To allow for longitudinal analysis and to address the issue of right-censoring, the data were reformatted to a person-data file. The selection criteria were limited to women living with HIV (WLHIV) who had also responded to the question on cervical cancer screening. Descriptive statistics were employed to show the levels of HIV among women aged 15 and older in South Africa. Additionally, Kaplan‒Meier curves were employed to investigate the time to CCS by WLHIV in South Africa. Thereafter, an unadjusted Cox hazards regression model was employed to examine the hazard of undergoing CCS among WLHIV. Finally, it employed an adjusted model to examine the hazard of CCS among WLHIV while adjusting for other factors. Nineteen percent (n = 1,159) of the women who participated in the study tested positive for HIV. Herein, it was found that the risk of CCS among WLHIV began at the age of approximately 19 years. Thereafter, the hazard of undergoing CCS among WLHIV began to decrease at 58 years. There was a significant association between CCS and WLHIV. Additionally, several covariates were found to be significantly associated with HIV. These were race, province, area of residence, marriage, educational attainment, employment, alcohol consumption, perceived health perception, and health insurance. The hazard of CCS was lower among WLHIV compared to WLHIV who did not undergo CCS in South Africa. This puts HIV-positive women at risk of increased morbidity and mortality from potential cervical cancer and HIV comorbidity due to CCS deficits within this group. This is because they are susceptible to HPV and subsequent cervical cancer due to a compromised immune system. HIV-positive women need to routinely undergo CCS every 12 months from baseline for 3 years. Thereafter, they should undergo CCS once every 3 years to reduce their risk of developing the disease.