Population-based trends in volumes and rates of ambulatory lumbar spine surgery.
METHODS
Sequential cross-sectional study.


OBJECTIVE
To quantify patterns of outpatient lumbar spine surgery.


BACKGROUND
Outpatient lumbar spine surgery patterns are undocumented.


METHODS
We used CPT-4 and ICD-9-CM diagnosis/procedure codes to identify lumbar spine operations in 20+ year olds. We combined sample volume estimates from the National Hospital Discharge Survey (NHDS), the National Survey of Ambulatory Surgery (NSAS), and the Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) with complete case counts from HCUP's State Inpatient Databases (SIDs) and State Ambulatory Surgery Databases (SASDs) for four geographically diverse states. We excluded pregnant patients and those with vertebral fractures, cancer, trauma, or infection. We calculated age- and sex-adjusted rates.


RESULTS
Ambulatory cases comprised 4% to 13% of procedures performed from 1994 to 1996 (NHDS/NSAS data), versus 9% to 17% for 1997 to 2000 (SID/SASD data). Discectomies comprised 70% to 90% of outpatient cases. Conversely, proportions of discectomies performed on outpatients rose from 4% in 1994 to 26% in 2000. Outpatient fusions and laminectomies were uncommon. NIS data indicate that nationwide inpatient surgery rates were stable (159 cases/100,000 in 1994 vs. 162/100,000 in 2000). However, combined data from all sources suggest that inpatient and outpatient rates rose from 164 cases/100,000 in 1994 to 201/100,000 in 2000.


CONCLUSIONS
While inpatient lumbar surgery rates remained relatively stable for 1994 to 2000, outpatient surgery increased over time.
Gray
Darryl T
DT
Center for Quality Improvement and Patient Safety, Agency for Healthcare Research and Quality, Rockville, MD 20850, USA. darryl.gray@ahrq.hhs.gov
Deyo
Richard A
RA
Kreuter
William
W
Mirza
Sohail K
SK
Heagerty
Patrick J
PJ
Comstock
Bryan A
BA
Chan
Leighton
L
D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data* / Q000639:trends*; D003430:Cross-Sectional Studies; D017586:Diskectomy / Q000706:statistics & numerical data / Q000639:trends; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data; D007796:Laminectomy / Q000706:statistics & numerical data / Q000639:trends; D008159:Lumbar Vertebrae / Q000601:surgery*; D009985:Orthopedics / Q000706:statistics & numerical data* / Q000639:trends*; D013123:Spinal Fusion / Q000706:statistics & numerical data / Q000639:trends; D014481:United States