... Quality of Life OutcomesOpen AccessResearch The longitudinal link between visual acuity and health- related quality of life in patients with diabetic retinopathyLouis S Matza*1, Matthew D ... Comparativeresponsiveness of generic and specific quality- of- life instru-ments. J Clin Epidemiol 2003, 56(1):52-60.39. Coons SJ, Rao S, Keininger DL, Hays RD: A comparative review of generic quality- of- life instruments. ... approval of the study protocoland the informed consent document. The study was initi-ated at each site after the principal investigator and the study sponsor obtained approval documents. The princi-pal...