Table 2.
Factors Independently Associated with Arterial Blood Gas or Pulse Oximetry Measurement among Outpatients
| Patients with Test, % | Adjusted Odds Ratio for Test (95% CI†) | |||||
|---|---|---|---|---|---|---|
| Factors* | Arterial Blood Gas (n = 45) | Pulse Oximetry (n = 172) | Either Test (n = 198) | Arterial Blood Gas | Pulse Oximetry | Either Test |
| Demographic | ||||||
| Age, y | ||||||
| ≤50 | 4.1 | 18.7 | 21.4 | 1.0 | ns‡ | 1.0 |
| 51–70 | 4.2 | 18.9 | 20.5 | 1.5 (0.7 to 3.6) | ns‡ | 1.6 (1.0 to 2.7) |
| >70 | 9.3 | 14.4 | 19.5 | 3.3 (1.5 to 7.2) | ns‡ | 2.0 (1.0 to 3.7) |
| Study Site | ||||||
| UPMC§ | 3.6 | 57.8 | 59.6 | 1.0 | 1.0 | 1.0 |
| SFMC§ | 4.1 | 42.9 | 42.9 | 1.1 (0.2 to 6.0) | 0.8 (0.4 to 1.9) | 0.8 (0.3 to 1.8) |
| MGH§ | 6.5 | 12.5 | 15.4 | 3.0 (1.0 to 8.5) | 0.2 (0.1 to 0.4) | 0.2 (0.1 to 0.4) |
| HCHP§ | 0.0 | 13.3 | 13.3 | 0.0 | 0.3 (0.2 to 0.7) | 0.3 (0.1 to 0.6) |
| VGH§ | 5.4 | 9.5 | 13.7 | 2.2 (0.8 to 6.3) | 0.1 (0.1 to 0.2) | 0.2 (0.1 to 0.3) |
| Clinical | ||||||
| Cardiopulmonary disease | ||||||
| No | 4.5 | 16.3 | 19.2 | ns‡ | 1.0 | ns‡ |
| Yes | 5.7 | 25.8 | 27.8 | ns‡ | 1.6 (1.0 to 2.6) | ns‡ |
| Dyspnea | ||||||
| No | 3.2 | 12.6 | 14.2 | ns‡ | 1.0 | 1.0 |
| Yes | 5.5 | 21.1 | 24.4 | ns‡ | 1.6 (1.0 to 2.5) | 1.9 ((1.2 to 2.9) |
| Respiratory rate, per minute | ||||||
| <25 | 7.6 | 32.6 | 36.7 | 1.0 | 1.0 | 1.0 |
| 25–29 | 16.7 | 43.3 | 56.7 | 2.4 (0.8 to 7.0) | 1.4 (0.6 to 3.1) | 2.0 (0.0 to 4.5) |
| ≥30 | 36.4 | 63.6 | 81.8 | 8.3 (2.1 to 33.3) | 3.2 (0.8 to 12.4) | 6.5 (1.3 to 32.3) |
| Not recorded | 0.6 | 2.1 | 2.6 | 0.1 (0.0 to 0.2) | 0.1 (0.1 to 0.3) | 0.1 (0.1 to 0.3) |
| Heart rate, per minute | ||||||
| <125 | 6.8 | 26.5 | 30.3 | ns‡ | 1.0 | 1.0 |
| ≥125 | 7.7 | 34.6 | 42.3 | ns‡ | 1.8 (0.7 to 4.8) | 2.0 (0.8 to 5.2) |
| Not recorded | 0.6 | 0.6 | 1.0 | ns‡ | 0.1 (0.0 to 0.4) | 0.1 (0.0 to 0.4) |
Patients missing vital sign measurements were included and labeled as “not recorded.” Patients missing other data (<1%) were excluded from the analysis. The following independent variables were considered in this logistic regression: age, gender, race, treatment site, membership in a health maintenance organization, dyspnea, respiratory rate, pulse, temperature, systolic blood pressure, smoking status, and underlying cardiopulmonary disease.
CI denotes confidence interval.
ns denotes not statistically significant.
UPMC indicates University of Pittsburgh Medical Center; SFMC, St. Francis Medical Center; MGH, Massachusetts General Hospital; HCHP, Harvard Community Health Plan–Kenmore Center; VGH, Victoria General Hospital.