Loss to Follow-Up as a Competing Risk in an Observational Study of HIV-1 IncidenceReportar como inadecuado




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Objective

Conventional survival estimates may be biased if loss to follow-up LTF is associated with the outcome of interest. Our goal was to assess whether the association between sexual risk behavior and HIV-1 acquisition changed after accounting for LTF with competing risks regression.

Methods

HIV-1-seronegative women who enrolled in a Kenyan sex worker cohort from 1993–2007 were followed prospectively and tested for HIV at monthly clinic visits. Our primary predictor was self-reported sexual risk behavior in the past week, analyzed as a time-dependent covariate. Outcomes included HIV-1 acquisition and LTF. We analyzed the data using Cox proportional hazards regression and competing risks regression, in which LTF was treated as a competing event.

Results

A total of 1,513 women contributed 4,150 person-years py, during which 198 13.1% acquired HIV-1 infection incidence, 4.5 per 100 py and 969 64.0% were LTF incidence, 23.4 per 100 py. After adjusting for potential confounders, women reporting unprotected sex with multiple partners were less likely to be lost to follow-up adjusted sub-hazard ratio aSHR 0.50, 95% confidence interval CI 0.32–0.76, relative to no sexual activity. The risk of HIV-1 acquisition after reporting unprotected sex with multiple partners was similar with Cox regression adjusted hazard ratio aHR 2.41, 95% CI 1.36–4.27 and competing risks regression aSHR 2.47, 95% CI 1.33–4.58.

Conclusions

Unprotected sex with multiple partners was associated with higher HIV-1 acquisition risk, but lower attrition. This differential attrition did not substantially bias Cox regression estimates when compared to competing risks regression results.



Autor: Susan M. Graham , Janet Raboud, R. Scott McClelland, Walter Jaoko, Jeckoniah Ndinya-Achola , Kishor Mandaliya, Julie Overbaugh, A

Fuente: http://plos.srce.hr/



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