Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Appendix B. Database Analysis

AHRQ's Healthcare Cost and Utilization Project (HCUP) State Ambulatory Surgery Database (SASD) databases were analyzed to identify the most common surgeries, the demographic profile of individuals receiving them, and the institutional profile of locations in which they are performed. Specifically, the 2006-2008 SASD databases for Maryland, New Jersey, and California were used in this study. Because the SASD database for California had data on both hospital-based and free-standing ASCs and included many variables that were of interest to this study, we analyzed the SASD California 2008 database extensively.1 We then extended this analysis to years 2006 and 2007, which produced results similar to those for 2008. This analysis resulted in a list of the top ten procedures for hospital-based and free-standing ASCs. We then analyzed the distribution of these procedures for hospital-based ASCs by the type of ownership (i.e., for-profit or not-for-profit) and by demographic characteristics. We repeated the same analysis for the top five surgical procedures requiring an incision for both hospital-based and free-standing ASCs.

In the California 2008 SASD, the total number of participating outpatient surgery centers was 831. There were 368 (44.28%) outpatient surgery centers that were hospital-based facilities and 463 (55.72%) that were free-standing facilities. The total number of records (including those records with some variables missing) was 2,852,294. Of these, 64.7% of the records were from hospital-based centers, while 35.3% of the records were from free-standing ASCs. More than 200 types of procedures were recorded as the patient's primary procedure in the database. Colonoscopy and biopsy, lens and cataract procedures, and upper gastrointestinal endoscopy and biopsy were the three most common primary procedures. In total, 35.04% of all the patients recorded them as their primary procedures. For pediatric patients, tonsillectomy and/or adenoidectomy, myringotomy, and oral and dental services were the three most common procedures, whereas for adult patients, colonoscopy and biopsy, insertion of catheter or spinal stimulator and injection into spinal cana, and lens and cataract procedures were the three most common procedures. Figures 1 and 2 present the top 10 procedures for hospital-based and free-standing outpatient surgery centers, respectively.

In California 2008 SASD, there were 65 (18.11%) government, non-federal outpatient surgery centers, 216 (60.17%) non-government not-for-profit centers, and 78 (21.73%) investor-owned for-profit ASCs. Among 1,818,577 records from hospital-based outpatient surgery centers, 14.29% of the records were from government, non-federal centers, 71.9% of the records were from non-government not-for-profit facilities, and 14.3% records were from investor-owned for-profit ASCs. Table 1 presents the frequency and percent distribution for top 10 procedures by ownership for hospital-based outpatient surgery centers only.

Table 1. Frequency and Percent Distribution for Top 10 Procedures for Hospital-Based Outpatient Surgery Centers Only (California 2008 SASD)

Government, Non Federal
Centers
Non-Government Not-For-Profit
Centers
Investor-Owned, For-Profit
Centers
CPT Procedures Freq % CPT Procedures Freq % CPT Procedures Freq %
Colonoscopy and biopsy 36,215 13.93% Colonoscopy and biopsy 175,817 13.44% Colonoscopy and biopsy 31,908 12.75%
Upper gastrointest. endoscopy, biopsy 20,661 7.95% Lens and cataract procedures 90,274 6.90% Upper gastrointest. endoscopy, biopsy 17,474 6.98%
Lens and cataract procedures 17,496 6.73% Upper gastrointest. endoscopy, biopsy 82,968 6.34% Insertion of catheter or spinal stimulator; injection into spinal canal 13,617 5.44%
Insertion of catheter or spinal stimulator; injection into spinal canal 11,059 4.25% Diagnostic cardiac catheterization, coronary arteriography 31,856 2.43% Lens and cataract procedures 13,118 5.24%
Excision of skin lesion 5,357 2.06% Insertion of catheter or spinal stimulator; injection into spinal canal 31,805 2.43% Excision of semilunar cartilage of knee 5,885 2.35%

In all, 29.1% of all the patients have a procedure with incision recorded as their primary procedures. Table 2 and Figure 3 display the frequency and percent distribution for top five surgical procedures with incision only.

Table 2.Frequency and Percent Distribution for Top 5 Surgical Procedures with Incision Only (California 2008 SASD)

Surgical procedures Total Hospital-based Freestanding
Freq % Freq % Freq %
Lens and cataract procedures 249,134 8.73% 121,716 6.60% 127,418 12.65%
Excision of semilunar cartilage of knee 67,742 2.38% 38,074 2.06% 29,668 2.95%
Other therapeutic procedures on muscles and tendons 65,773 2.31% 39,830 2.16% 25,943 2.58%
Inguinal and femoral hernia repair 48,674 1.71% 40,790 2.21% 7,884 0.78%
Other OR therapeutic procedures on joints 46,885 1.64% 26,558 1.44% 20,327 2.02%
Total 478,208 16.77% 266,968 14.47% 211,240 20.98%

Finally, the demographic data of patients with arthroscopic procedure (CPT code 29866-29889) in the California 2008 SASD dataset is presented in Table 3.

Table 3. Demographic Data of Patients Having Arthroscopic Procedures (California 2008 SASD)

Demographic Factor Total Hospital-Based Center Free-standing Center
Freq % Freq % Freq %
Age
< 1 month 0 0.00% 0 0.00% 0 0.00%
1-11 months (0) 2 0.00% 1 0.00% 1 0.00%
12-59 months (1-4 years) 3 0.00% 2 0.00% 1 0.00%
60 months to <12 years
(5-11 years)
941 1.02% 604 1.14% 337 0.85%
12 years to < 18 years 4,875 5.27% 3,248 6.13% 1,627 4.11%
18-44 years 29,344 31.70% 17,292 32.63% 12,052 30.44%
45-64 years 44,807 48.40% 24,849 46.90% 19,958 50.41%
65-84 years 12,282 13.27% 6,779 12.79% 5,503 13.90%
>85 years 326 0.35% 212 0.40% 114 0.29%
Total 92,580 100% 52,987 100% 39,593 100%
Gender
Male 43,901 54.61% 25,807 54.32% 18,094 55.04%
Female 36,486 45.39% 21,703 45.68% 14,783 44.96%
Total 80,387 100% 47,510 100% 32,877 100%
Payer
Medicare 13,530 14.01% 7,540 13.76% 5,990 14.33%
Medicaid 2,460 2.55% 2,251 4.11% 209 0.50%
Private insurance 64,694 66.98% 38,115 69.57% 26,579 63.60%
Self-pay 993 1.03% 474 0.87% 519 1.24%
Other 14,903 15.43% 6,407 11.69% 8,496 20.33%
Total 96,580 100% 54,787 100% 41,793 100%
Patient Residence
Metro - 1 million population+ 67,895 70.36% 37,521 68.56% 30,374 72.73%
Metro - 250,000 to 1 million population 18,686 19.37% 11,290 20.63% 7,396 17.71%
Metro - fewer than 250,000 population 6,418 6.65% 3,365 6.15% 3,053 7.31%
Non-Metro - Urban population of 20,000 +, adjacent to a metro area 1,475 1.53% 1,035 1.89% 440 1.05%
Non-Metro - Urban population of 20,000 +, not adjacent to a metro area 439 0.45% 417 0.76% 22 0.05%
Non-Metro - Urban population of 2,500 - 19,999, adjacent to a metro area 785 0.81% 487 0.89% 298 0.71%
Non-Metro - Urban population of 2,500 - 19,999, not adjacent to a metro area 636 0.66% 547 1.00% 89 0.21%
Non-Metro - Completely rural or <2,500 urban population, adjacent to a metro area 151 0.16% 66 0.12% 85 0.20%
Non-Metro - Completely rural or <2,500 urban population, not adjacent to a metro area 5 0.01% 0 0.00% 5 0.01%
Total 96,490 100% 54,728 100% 41,762 100%
Race
White 45,220 74.81% 28,846 73.57% 16,374 77.09%
Black 1,669 2.76% 1,323 3.37% 346 1.63%
Hispanic 10,459 17.30% 7,248 18.49% 3,211 15.12%
Asian or Pacific Islander 1,768 2.92% 1,282 3.27% 486 2.29%
Native American 44 0.07% 25 0.06% 19 0.09%
Other 1,288 2.13% 484 1.23% 804 3.79%
Total 60,448 100% 39,208 100% 21,240 100%

1 Note that the New Jersey SASD database did not contain data on free-standing ASCs, whereas both the Maryland and California SASD databases did. However, the California SASD database included more variables that were of interest to this study and also included many more records than the Maryland database.

Page last reviewed April 2013
Internet Citation: Appendix B. Database Analysis. April 2013. Agency for Healthcare Research and Quality, Rockville, MD. http://www.ahrq.gov/research/findings/final-reports/stpra/stpraapb.html