ali keshtkaran school of management and medical information sciences, shiraz university of medical sciences, shiraz, ir iran alireza mirahmadizadeh shiraz aids research center, shiraz university of medical sciences, shiraz, ir iran; shiraz aids research center central building of shiraz university of medical sciences, 8th floor, zand blvd., shiraz, ir iran. tel: +98-7112122320 alireza heidari health management and social development research center, golestan university of medical sciences, gorgan, ir iran mehdi javanbakht health economics research unit, institute of applied health sciences, university of aberdeen, aberdeen, uk

H M Smith G J Alexander G Webb T McManus I G McFarlane R Williams