In a study on comparison of a common drug (NSAID) and a rare drug (Dypirone) causing disease, the relative risk (RR) andattributable risk (AR) were calculated. The true statement is :
Ans. is 'b' ie NSAID has higher RR and AR than dipyrone Park or any other book eg. High Yield biostatistics, NMS biostatistics do not give any explanation about this question.They give the definitions only. The question has to be worked upon these definitions by applying simple logics. ,Relative Risk = ((Incidence of disease among exposed) / (Incidence of disease among non- exposed)) x 100Incidence of disease rate among exposed minus - incidense of disease rate among non-exposed. 3/4 Attributable Risk = ; x 100Incidence rate among exposedApplying logics some points become clear about a commonly used NSAID and a rarely used Dipyrone.Incidence of disease among exposed is low for NSAID and high for Dipyrone (that's the reason why NSAID is commonly used and Dipyrone rarely used)Incidence of disease among non exposed, for NSAID would be very less and can be nullified (as very few persons would be left unexposed, Can you name anyone whose has not taken, crocein or disprin)Let's see the Attributable risk firstIn this formula, 'incidence of disease among non - exposed* is a negative variable.Thus the lesser the value of this negative variable the higher would be AR.As NSAID has a lesser value (or even negligible) of this negative variable its AR would be higher than that of Dipyrone.Now the Relative RiskEven though the 'incidence of disease among exposed' is low for NSAID than Dipyrone its RR would be falsely higher as the variable 'incidence of disease among non - exposed* lying in the denominator and being negligible of NSAID would prove to be the deciding factor.The lesser the value of the variable 'incidence of ds. among non - exposed' the higher would be the RR.Note thatEven though the 'incidence of ds among exposed' is high for Dipyrone its relative risk comes to be falsely low.This is because, it is very rarely used due to its high side effects (Dipyrone is known to cause agranulocytosis and is banned in India )This is a fallacy of the formulae for RR&AR which does take into consideration the number of person using the drug.Very logically a drug that is not used at all would have Zero RR & AR.
NSAID has lower RR and AR than Dypirone
NSAID has higher RR and AR than Dypirone
NSAID has lower RR and higher AR than Dypirone
AR and RR of both are same.
Analytical Epidemiology