Table 3.
Adjusted Associations of Preoperative Pain Levels and Risk for Delirium*
| Pain Measure | Worst | Average | Current | |||
|---|---|---|---|---|---|---|
| Level | n/N (%) | Adjusted RR (95% CI) | n/N (%) | Adjusted RR (95% CI) | n/N (%) | Adjusted RR (95% CI) |
| None/Mild† | 13/71 (18) | Referent | 29/145 (20) | Referent | 71/331 (21) | Referent |
| Moderate | 21/104 (20) | 1·1 (0·6–2·0) | 44/205 (21) | 1·0 (0·7–1·6) | 16/85 (19) | 0·9 (0·5–1·4) |
| Severe | 72/284 (25) | 1·3 (0·8–2·2) | 33/105 (31) | 1·4 (0·9–2·3) | 19/43 (44) | 2·0 (1·4–3·0) |
|
| ||||||
| Ptrend: | 0·146 | --- | 0·045 | --- | 0·013 | --- |
*
RR= Relative risk for delirium. Pain is modeled as a three-level categorical variable. Risk estimates are adjusted for age, gender, race, education level, and comorbidity. CI=confidence interval. n/N=fraction of delirious patients in pain category. The Cochran-Armitage test was used to whether the proportion of delirium is constant across pain categories. A significant Ptrend (≤0·05) indicates that rate of delirium changes linearly across increasing levels of pain.
†
None and mild pain levels were combined because few subjects rated worst or average pain with scores of 0.