Incidence rate and risk factors for loss to follow-up in a French clinical cohort of HIV-infected patients from January 1985 to January 1998

Objectives To determine the incidence rate and risk factors for loss to follow-up (LFU) in HIV-infected individuals. Methods We estimated the incidence rate of LFU in 1756 HIV-infected patients enrolled in the Tourcoing Clinical Cohort from January 1985 to January 1998. We then investigated potential LFU risk factors at inclusion through a case-control study. Cases were 209 patients who had attended neither our clinic nor another HIV clinic for at least 1 year. Controls were 209 patients randomly selected from the group of HIV-infected patients followed up regularly. Results The incidence of LFU was estimated at 4.3 per 100 person-years [95% confidence interval (CI) 3.7-4.9]. Independent risk factors for LFU were (i) year of enrolment before 1993 [odds ratio (OR) 6.7; 95% CI 2.7-16.5 versus after 1997]; (ii) year of enrolment between 1993 and 1997 (OR 5.1; 95% CI 2.0-13.0 versus after 1997); (iii) age < 30 years (OR 1.8; 95% CI 1.0-3.5 versus > 40 years); (iv) injecting drug use (OR 5.3; 95% CI 2.7-10.5 versus men who have sex with men); (v) homelessness and/or illegal immigrant status (OR 2.2; 95% CI 1.0-4.9); and (vi) lack of a primary care provider (OR 6.0; 95% CI 2.4-15.1). A history of an AIDS-defining illness (OR 0.3; 95% CI 0.2-0.6) and a history of psychiatric disease (OR 0.4; 95% CI 0.3-0.8) were both associated with a decreased risk of LFU. Conclusions This study assessed the sociodemographic, clinical and behavioural characteristics associated with LFU in HIV-infected patients. The findings of this study may allow clinicians to identify patients at risk of LFU, so that appropriate interventions may be initiated.