Which of the following will cause an increase in the prevalence of disease?

Prevalence depends upon 2 factors, the incidence (I) and duration of illness (D). Given the assumption that the population is stable, and incidence and duration are unchanging, the relationship between incidence and prevalence is, P = I* D = Incidence * mean duration Therefore when duration increases prevalence also increases. Ref: Park's Textbook of Preventive and Social Medicine, By K. Park, 19th Edition, Page 57; How to Repo Statistics in Medicine By Thomas Allen Lang, 2nd Edition, Pages 165-6