The Timing of Corticosteroid Injections after Shoulder Arthroscopy Affects Postoperative Infection Risk

Abstract

Objectives:

To examine the association between the timing of post-operative corticosteroid injections with rates of post-operative infection in arthroscopic shoulder procedures.

Methods:

Private-payer and Medicare national insurance databases were queried for patients who underwent arthroscopic rotator cuff repair, debridement, or subacromial decompression. Patients who underwent corticosteroid injections within 1 month, 2 months, 3 months, or 4 months post-operatively were identified and compared to a matched control group that underwent the same surgeries without a postoperative steroid injection. ICD-9 and CPT codes were used to identify rates of post-operative infection within 90 days after injection for the study groups and controls. Multivariate binomial logistic regression analysis was used to compare groups and adjusted odds ratios (OR) and 95% confidence intervals were calculated with p< 0.05 considered significant.

Results:

A total of 3,946 patients were identified, including 264 patients who received an injection within 1 month after surgery, 471 within 2 months, 1,037 within, 1,874 within 4 months, and 2,640 matched controls. Compared to controls, patients who underwent a corticosteroid injection within 1 month postoperatively had a significantly higher rate of infection (PP: OR 2.63, p=0.014; MC: OR 11.2, p<0.0001). There were no differences in infection rates at all other time points: (p =0.264 -0.835).

Conclusion:

This study adds to the evidence suggesting caution when administering injections in the immediate post-operative period following arthroscopic shoulder surgery. Although causality cannot be determined on the basis of this administrative database review, we found a significant association between intra-articular ipsilateral corticosteroid injections administered 1 month post-operatively and an increased rate of post-operative infection, in both a Medicare and private payer patient cohort, when compared to a control patient group.

Table 1.

Infection Rate Stratified by Post-Operative Injection Timing (Humana)

	Infection Rates			Statistical Comparison to Controls
Post op Time Point	N Patients	# of Infections	Infection Rate	O.R. [95% CI]	P
1 Month	144	5	3.5%	2.63 [1.32-5.22]	0.014
2 Months	350	1	0.3%	0.89 [0.23-3.36]	0.264
3 Months	405	2	0.5%	0.71 [0.26 -1.94]	0.534
4 Months	749	2	0.3%	0.87 [0.27-2.86]	0.484
Matched Controls	1,440	7	0.5%	-	-

Table 2.

Infection Rate Stratified by Post-Operative Injection Timing (Medicare)

	Infection Rates			Statistical Comparison to Controls
Post op Time Point	N Patients	# of Infections	Infection Rate	O.R. [95% CI]	P
1 Month	120	8	6.7%	11.2 [2.33-53.57]	<0.0001
2 Months	421	2	0.5%	1.52 [0.29-8.11]	0.516
3 Months	632	2	0.3%	1.27 [0.36-4.53]	0.798
4 Months	1,125	3	0.3%	0.82 [0.19-3.48]	0.835
Matched Controls	1,200	4	0.3%