Estimate the odds ratio for Group C vs. Group A and provide a 95% CI. Are the results consistent with those in Problem 13.21? Why or why not? 

One assumption in Table 13.46 is that the log odds ratio of being a case is a linear function of the lifetime acetaminophen intake. To check this assumption, a second logistic regression was run relating disease status to acetaminophen intake in categories using the categories in Table 13.45 with Group A as the reference and Groups B, C, and D denoted by .Iacetam ~300, .Iacetam ~1750, .Iacetam ~4000, respectively (see Table 13.47).

Table 13.46: Logistic Regression relating decrease in GFR of ‰¥ 30% over 11 years vs. lifetime acetaminophen intake/100 (continuous variable)

 

Table 13.47: Logistic Regression relating decrease in GFR of ‰¥ 30% over 11 years vs. lifetime acetaminophen intake (categories)

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logit case ace_100 [fweight=freq] Iteration 0: log likelihood = -548.9024 Iteration 1: log likelihood = -543.33838 Iteration 2: log likelihood = -543.21443 = -543.21438 Iteration 3: log likelihood Logistic regression Number of obs = 1645 LR chi2 (2) = 11.38 Prob > chi2 = 0.007 Log 11kelihood = -543.21438 Pseudo R2 = 0.0104 P>|z| Std. Err. Coef. [95% Conf. Interval] case .0164116 .0047713 3.44 0.001 .00706 .0257633 ace_ 100 -2.381986 1101246 -21.63 0.000 -2.597826 -2.166146 cons xi:logit case 1.acetaminophen [fweight 1.acetaminoph-e Iteration 0: log likelihood = -548.9024 freq) _Iacetamino_50-4000 (naturally coded; Iacetamino 50 omitted) Iteration 1: log likelihood = -542.90745 Iteration 2: log likelihood = -542.77438 Iteration 3: log likelihood = -542.77432 Iteration 4: log likelihood = -542.77432 Logistic regression Number of obs 1645 LR chi2 (3) 12.26 Prob > ch12 0.0066 Log likelihood = -542.77432 Pseudo R2 0.0112 --- | Coef. Std. Err. P>|z| [95% Conf. Interval] case --- _Iacetam-300 .2608557 .2740422 0.95 0.341 -.2762572 .7979685 Iaceta-1750 .4234367 .2232226 1.90 0.058 -.0140714 .8609449 Iaceta-4000 .6818717 .1975946 3.45 0.001 .2945934 1.06915 cons -2.43441 .1283726 -18.96 0.000 -2.686016 -2.182805