For this question we will be reviewing Table 2 from the following article:Coogan PF et al. Experiences of Racism and the Incidence of Adult-Onset Asthma in the Black Women's Health Study. 2014 Chest 145(3):480-485. (Please treat IRR as RR)

Question: Interpret the crude IRRfor the association of everyday racism (4^thquartile vs 1^stquartile) and adult-onset asthma. (what does this mean or indicate?)

Crude incidence rate ratio (IRR): (304/108172)/ (152/85334) = 1.58

Table 2-Everyday and Lifetime Racism Scores in 1997 and Asthma Incidence, BWHIS, 1997-2011 Scores No. of Cases (Person-y) Age- and Period-Adjusted IRR (95% CI) Multivariable IRR. (95 CI) Everyday racism score Quartile 1 152 (85,334) 1.00 (Ref) 1.00 (Ref) Quartile 2 283 (131,042) 1.23 (1.01-1.50) 1.19 (0.98-1.46) Quartile 3 329 (129,759) 1.48 (1.21-1.79) 1.39 (1.14-1.69) Quartile 4 304 (108,172) 1.68 (1.37-2.04) 1.45 (1.19-1.78) P for trend <.0001 lifetime racism score no to all yes p for trend irr incidence rate ratio ref="reference." see table legend expansion of other abbreviation. age time period bmi kp missing current smoker pack-y smok- ing secondhand smoke exposure y at home or work and currently vigorous exercise in w alcohol use drinks past any amount female hormone parental history asthma unknown mother smoking status education years household income> $100,000, missing)