Table II.

Opioid user (OU) versus non-opioid user (NOU) filling opioid prescriptions following UKA

UKA	OU		NOU		OU vs NOU
mths	Patients filling opioid Rx	%	Patients filling opioid Rx	%	Risk ratio	95% Confidence interval
1	1111	81.57	999	57.65	1.42	1.35 to 1.48
2	674	49.49	231	13.33	3.71	3.26 to 4.23
3	487	35.76	112	6.46	5.53	4.56 to 6.71
4	434	31.86	78	4.50	7.08	5.62 to 8.91
5	397	29.15	64	3.69	7.89	6.12 to 10.18
6	382	28.05	55	3.17	8.84	6.72 to 11.62
7	363	26.65	56	3.23	8.25	6.28 to 10.83
8	375	27.53	56	3.23	8.52	6.49 to 11.18
9	380	27.90	59	3.40	8.20	6.29 to 10.68
10	359	26.36	60	3.46	7.61	5.85 to 9.91
11	369	27.09	72	4.15	6.52	5.12 to 8.31
12	349	25.62	65	3.75	6.83	5.29 to 8.82

CI, confidence interval; Rx, prescription; UKA, unicompartmental knee arthroplasty