1. Health Services Research Group, IMIM Hospital del Mar Medical Research Institute, Barcelona, Spain.
2. Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Spain.
3. Department of Pediatrics, Obstetrics and Gynecology and, Preventive Medicine and Public Health, Universitat Autònoma de Barcelona, Barcelona, Spain.
4. Department of Health, Behavior and Society, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
5. Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona, Spain.
6. Center for HIV Surveillance, Epidemiology and Evaluation, Maryland Department of Health, Baltimore, Maryland.