Objective: Proteinuria occurs commonly among HIV-infected and uninfected injection drug users (IDUs) and is associated with increased mortality risk. Vitamin D deficiency, highly prevalent among IDUs and potentially modifiable, may contribute to proteinuria. To determine whether vitamin D is associated with proteinuria in this population, we conducted a cross-sectional study in the AIDS Linked to the IntraVenous Experience (ALIVE) Study.
Methods: 25(OH)-vitamin D levels were measured in 268 HIV-infected and 614 HIV-uninfected participants. The association between vitamin D deficiency (<10 ng/ml) and urinary protein excretion was evaluated by linear regression. The odds of persistent proteinuria (urine protein-to-creatinine ratio >200 mg/g on two occasions) associated with vitamin D deficiency was examined using logistic regression.
Results: One-third of participants were vitamin D-deficient. Vitamin D deficiency was independently associated with higher urinary protein excretion (P < 0.05) among HIV-infected and diabetic IDUs (P-interaction < 0.05 for all). Persistent proteinuria occurred in 18% of participants. Vitamin D deficiency was associated with greater than six-fold odds of persistent proteinuria among diabetic IDUs [odds ratio (OR) 6.29, 95% confidence interval (CI) 1.54, 25.69] independent of sociodemographic characteristics, comorbid conditions, body mass index, and impaired kidney function [estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m2]; no association, however, was observed among nondiabetic IDUs (OR 1.06, 95% CI 0.64, 1.76) (P-interaction <0.05).
Conclusions: Vitamin D deficiency was associated with higher urinary protein excretion among those with HIV infection and diabetes. Vitamin D deficiency was independently associated with persistent proteinuria among diabetic IDUs, although not in nondiabetic persons. Whether vitamin D repletion ameliorates proteinuria in these patients requires further study.
aDepartment of Medicine, Johns Hopkins University School of Medicine
bDepartment of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA.
Correspondence to Michelle M. Estrella, MD, MHS, Assistant Professor of Medicine, Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, 1830 E. Monument St., Ste. 416, Baltimore, MD 21205, USA. Tel: +1 410 955 5268; fax: +1 410 955 0485; e-mail: email@example.com
Received 29 September, 2011
Revised 4 November, 2011
Accepted 14 November, 2011