Table 4.

Adjusted risk ratios^* (95% CIs) and P values^† for persistent opioid use (three definitions) in patients who received tramadol only, tramadol and another short acting opioid, or any long acting opioids (reference group: short acting opioids excluding tramadol)

Opioid type	Additional opioid use after surgery‡	Persistent opioid use after surgery§	CONSORT definition of opioid dependence¶
Other short acting	Reference	Reference	Reference
Tramadol only	1.06 (1.00 to 1.13); P=0.049	1.47 (1.25 to 1.69); P<0.001	1.41 (1.08 to 1.75); P=0.013
Tramadol plus short acting	1.05 (0.96 to 1.14); P=0.261	1.04 (0.86 to 1.21); P=0.685	1.40 (1.05 to 1.74); P=0.022
Any long acting	0.95 (0.87 to 1.03); P=0.218	1.18 (1.02 to 1.35); P=0.029	1.69 (1.36 to 2.02); P<0.001

^*Risk ratios calculated as ratio of predictive margins after logistic regression including covariates of year, surgery, female sex, beneficiary type, race/ethnicity, census division, age category, categorical measurement of morphine milligram equivalents at discharge, and flags for each of Elixhauser comorbidities; see appendix F for full regression output.

^†P values from hypothesis test that risk ratio does not equal 1.

^‡At least one opioid fill 90-180 days after surgery.

^§Any span of opioid use starting in 180 days after surgery and lasting ≥90 days.

^¶Opioid use episode starting in 180 days after surgery that spans ≥90 days and includes either ≥10 opioid fills or ≥120 days’ supply of opioids.