Question

Quintile Incidence Rate per 100,000 person-years 26.61 cases per 100,000 person-years 98 cases 304,999 person-years 32.13 cases per 100,000 person-years 82 cases /308,186 person-years 2 86 cases / 298,493 person-years-28.81 cases per 100,000 person-years 113 cases /294,802 person-years-38.33 cases per 100,000 person-years 102 cases / 286,070 person-years 35.66 cases per 100,000 person-years 4 5 Overall (crude) 481 cases/1,492,550 person-years 32.23 cases per 100,000 person-years IR b) Calculate the unadjusted relative risk for quintiles 2-5 of dietary vitamin Be, using quintile 1 as the reference (non-exposed) group, and clearly showing the numerator denominator used for the calculation. (1 points) and Quintile Relative Risk Reference 2 5

Answer 1

In the given table, we are provided with the incidence rates for quintiles, where quintile 1 is the reference group. Relative risk is basically calculated to analyze the strength of association between a particular factor and disease or related outcome. The ratio between two groups(one unaffected and the other affected) incidences gives the relative risk. It is greater than or equal to 0. If it is 1, then the probability for occurrence or non-occurrence of a disease would be the same. If it comes out to be 0, then it indicates no probability of a particular event occurring. So the relative risk(risk ratio)for -

(a) Quintile 2 - Incidence rate(IR) of quintile2/ IR of quintile 1(Control) = 32.13/26.61 = 1.2

(b) Quintile 3 - IR of quintile 3 / IR of quintile 1 = 28.81/26.61 = 1.08

(c) Quintile 4 - IR of quintile 4 / IR of quintile 1 = 38.33/26.61 = 1.44

(d) Quintile 5 - IR of quintile 5 / IR of quintile 1 = 35.66/26.61 = 1.34