<prompt> A drug, which does not cure a disease but decreases its symptoms and increases survival, leads to?Increased prevalenceIncreased incidenceDecreased prevalenceDecreased incidence  <response>: Ans. a. Increased prevalence Ref: Park 23e p61, 22e p59A drug, which does not cure a disease but decreases its symptoms and increases survival, means its leads to increased duration of disease and increased prevalence.Prevalence No. of total old new cases of a disease in a yearTotal population x 100 Prevalence Incidence x Mean duration of diseasePrevalence is the proportion of a population that has a condition at a specific time, but the prevalence will be influenced by both the rate at which new cases are occurring and the average duration of the disease. Incidence reflects the rate at which new cases of disease are being added to the population and becoming prevalent cases. Average duration of disease is also important, because the only way you can stop being a prevalent case is to be cured or to move out of the population or die. PrevalencePrevalence is the total current Old new cases in a given population over a point or period of timeQ.Types: Point prevalence at a point of time Period prevalence over a period of timeQPrevalence No. of total old new cases of a disease in a yearTotal population x 100QPrevalence is a proportion, not a ratio: Numerator is a part of denominator, and is always expressed in percentage.Prevalence can be determined from cross-sectional studyQ.Relation between Incidence PrevalenceGiven the assumption that population is stable incidence and duration are not changing.Prevalence Incidence x Mean duration of diseaseQPrevalence describes balance between incidence, mortality and recoveryQ.Incidence reflects causal factorsQ.Duration reflects prognostic factorsQ 