820 infection control & hospital epidemiology july 2017, vol. 38, no. 7
table 2. Characteristics of Hospitals and Patients Who Under- went Orthopedic Procedures
Variable
Age mean (SE) Female (%)a
Hospital region (%) Northeast Midwest South West
Hospital location and teaching statusb (%) Rural
Urban nonteaching
Urban teaching or missing
Elective admission (%)c Race (%)d White Black
Hispanic
Other or missing Comorbidities (%) 1
SSI (%) None
2 or more
Median household income for patient ZIP code, $e 1–38,999
39,000–47,000 48,000–62,999 >63,000 Missing
Non-Medicare (n=607,844)
64.1 (.01) 51.9
15.2 21.8 41.0 22.0
4.4
41.6 54.0
80.0 67.7
5.9 4.0
22.4 0.5
21.2 29.7 49.1
17.8 24.0 26.2 29.7 2.3
Medicare
59.0 13.0
22.6 44.1 20.3
<.001 6.0
42.9 51.1
80.4 71.7
5.1 3.5
19.7 0.6
14.5 27.0 58.5
<.001
21.0 26.3 25.9 24.8 2.0
NOTE. SSI, surgical site infection; SE, standard error. aMissing 0.02% of observations. bMissing 0.5% of observations. cMissing 7.8% of observations. dMissing 17.6% of observations. eMissing 2.0% of observations.
(RR, 0.9; 95% CI, 0.8–1.1). Second, we found that clustering patients by hospital in a hierarchical regression model showed similar results (RR, 0.9; 95% CI, 0.8–1.1). Third, we examined the policy effect using 3 separate controls: 60–64-year-old patients not in Medicare (RR, 1.0; 95% CI, 0.8–1.3), 65–69- year-old patients with private insurance (RR, 1.0; 95% CI, 0.8– 1.3), and 60–80-year-old patients with Medicare undergoing nontargeted spine, shoulder, and elbow procedures (RR, 0.9; 95% CI, 0.5–1.4). Finally, we tested the results in 3 diverse, all- capture state claims datasets (SID) from 2005 to 2011 (ie, from California, Florida, and New York) (RR, 1.2; 95% CI, 0.9–1.7). We also ran another analysis that included SSIs occurring 30 days postdischarge (RR, 1.1; 95% CI, 0.9–1.3). Overall, all analyses showed the same general results.
.01 <.001
<.001 <.001
P
(n=1,146,010) Value 70.6 (.01) <.001
<.001 <.001
Medicare
Non-Medicare Difference
table 3. Changes in Surgical Site Infection Rates by Payer Status, 2000–2013a
No. of SSI per 1,000 Orthopedic Procedures
7.0 5.9 1.1
5.2 4.9 0.3
−1.8 −1.0 −0.8
Model Estimates SSI Rate Ratio
Prepolicy Postpolicy Change Adjusted RR 95% CI 0.7b
0.8c 0.9d
NOTE. SSI, surgical site infection; CI, confidence interval. aThe model was unweighted and adjusted for age, sex, race, and
median household income for patient’s zip code, comorbidities, elective admission, and hospital characteristics including hospital region and hospital teaching status. The interaction of postpolicy period and payer status variable was the difference-in-difference estimate. Any discharge before October 1, 2008, was considered to
have occurred in the prepolicy period. bP<.0001. cP=.0006. dP=.2821.
discussion
Our results suggest that the provision of the 2008 CMS never- event policy that prohibited extra costs for treating SSIs fol- lowing certain orthopedic procedures was not associated with a significant change in SSI rates following policy imple- mentation among the Medicare population compared to similarly aged adults unaffected by the policy.Wedid identify a significant decrease in SSI rates pre- versus postpolicy in both the Medicare and non-Medicare populations. However, con- sidering already decreasing SSI rates prior to policy imple- mentation, the reduction in SSI rates was likely a continuation of prepolicy trends. Overall, we could not associate this change with the CMS nonpayment policy with a reduction in SSI rates among Medicare patients compared to our control group. There are several possible reasons for the lack of significance. First, sig- nificant decreasing secular trends for orthopedic SSI rates prior to the CMS policy have been reported.21 SSIs after these select orthopedic procedures are already rare events, so the added effect by this provision may be minimal. Others have suggested that the overall cost implications of this policy would be minor.22 Given the professional norms of preventing and caring for patients with SSIs and minimal financial disin- centives imposed by the policy, the measureable effect of the CMS nonpayment policy for SSI following certain orthopedic procedures might be limited.22 Additionally, during the study period, other SSI prevention
strategies were already in place.6 The National Surgical Infection Prevention Project developed guidelines for prophylaxis timing and concentrations following orthopedic surgeries.23 The Joint Commission and Association for Professionals in Infection Control had established guidelines to eliminate orthopedic SSIs that focused on teamwork and facility-wide interventions to
(0.6–0.8) (0.7–0.9) (0.8–1.1)
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