Table 2.
All-cause and AS-specific healthcare utilization, 12-month follow-up
| Matched controls N = 19,951 |
Patients with AS N = 6679 |
P valueb | ||
|---|---|---|---|---|
| All-cause utilization | All-cause utilization | AS-specific utilizationa | ||
| Inpatient admission | ||||
| Patients with any inpatient admission, n (%) | 1171 (5.9) | 776 (11.6) | 72 (1.1) | < 0.001 |
| Number of inpatient admissions, per patient per year, among those with ≥ 1 admission, mean (SD) | 1.20 (0.72) | 1.44 (0.96) | 1.08 (0.24) | < 0.001 |
| Length of stay per admission, mean (SD) | 5.43 (13.33) | 5.04 (4.90) | 7.75 (10.98) | 0.432 |
| Days to first inpatient admission from index date, mean (SD) | 176.17 (106.45) | 144.61 (113.26) | 95.61 (109.83) | < 0.001 |
| Emergency department (ED) | ||||
| Patients with any ED visit, n (%) | 3057 (15.3) | 1504 (22.5) | 153 (2.3) | < 0.001 |
| Number of ED visits, per patient per year, among those with ≥ 1 ED visit, mean (SD) | 1.44 (1.20) | 1.68 (1.56) | 1.08 (0.60) | < 0.001 |
| Days to first ED visit from index date, mean (SD) | 166.04 (105.78) | 150.76 (105.76) | 129.33 (125.34) | < 0.001 |
| Nonhospital-based outpatient visits | ||||
| Patients with any nonhospital-based visit, n (%) | 16,801 (84.2) | 6658 (99.7) | 6251 (93.6) | < 0.001 |
| Number of outpatient office visits, per patient per year, mean (SD) | 5.52 (5.40) | 10.56 (7.56) | 3.36 (2.76) | < 0.001 |
| Hospital-based outpatient visits | ||||
| Patients with any hospital-based outpatient visits, n (%) | 9096 (45.6) | 4542 (68.0) | 1741 (26.1) | < 0.001 |
| Number of hospital-based outpatient visits, per patient per year, mean (SD) | 3.60 (5.40) | 5.16 (6.60) | 2.40 (2.64) | < 0.001 |
| Other outpatient services | ||||
| Patients with any other outpatient service, n (%) | 16,199 (81.2) | 6488 (97.1) | 4473 (67.0) | < 0.001 |
| Number of other outpatient services, per patient per year, mean (SD) | 8.28 (12.00) | 14.16 (15.72) | 3.84 (5.16) | < 0.001 |
AS ankylosing spondylitis, ICD-9-CM International Classification of Diseases, Ninth Revision, Clinical Modification
aAS-specific healthcare resource utilizations were defined as inpatient or outpatient claims with the diagnosis code for AS (ICD-9-CM 720.0) and AS medications. The outpatient diagnosis could be in any position. The inpatient diagnosis was required to be primary discharge diagnosis, and the whole hospitalization stay was considered AS specific
bMatched controls vs patients with AS for all-cause utilization