Selected baseline characteristics, before and after propensity score matching, of patients with physician-diagnosed COPD who did and did not receive pulmonary function testing in the peridiagnostic period*
| Characteristic | Before propensity score matching | After propensity score matching | ||||||
|---|---|---|---|---|---|---|---|---|
| Testing in peridiagnostic period | Standardized difference, % | p value† | Testing in peridiagnostic period | Standardized difference, % | p value† | |||
| Yes | No | Yes | No | |||||
| Patients, n | 28 386 | 40 512 | 17 783 | 17 783 | ||||
| Demographic characteristics | ||||||||
| Age, yr, mean ± SD | 66.86 ± 11.53 | 70.27 ± 13.31 | 0.3 | < 0.001 | 67.20 ± 11.87 | 67.20 ± 11.88 | 0.00 | 1.0 |
| Women, % | 47.4 | 49.4 | 0.04 | < 0.001 | 47.4 | 47.4 | 0.00 | 1.0 |
| Income quintile, % | ||||||||
| 1 (lowest) | 22.6 | 25.7 | 0.07 | < 0.001 | 24.1 | 24.2 | 0.00 | 0.9 |
| 2 | 21.5 | 22.3 | 0.02 | 22.2 | 22.4 | 0.01 | ||
| 3 | 19.8 | 19.3 | 0.01 | 19.8 | 19.5 | 0.01 | ||
| 4 | 18.7 | 17.4 | 0.03 | 18.0 | 17.8 | 0.00 | ||
| 5 (highest) | 17.4 | 15.4 | 0.05 | 16.0 | 16.1 | 0.00 | ||
| Rural (v. urban) residence, % | 13.1 | 17.9 | 0.1 | < 0.001 | 15.3 | 15.9 | 0.01 | 0.2 |
| Immigrant, % | 7.3 | 6.5 | 0.03 | < 0.001 | 7.2 | 7.2 | 0.00 | 0.9 |
| Living in long-term care, % | 0.9 | 7.9 | 0.3 | < 0.001 | 1.3 | 1.2 | 0.01 | 0.3 |
| COPD-related characteristics, % | ||||||||
| Ambulatory during the peridiagnostic period | 70.5 | 43.7 | 0.6 | < 0.001 | 62.6 | 62.6 | 0.00 | 1.0 |
| Spirometry before peridiagnostic period | ||||||||
| Up to 1 yr before | 13.4 | 5.2 | 0.30 | < 0.001 | 8.4 | 8.3 | 0.00 | 1.0 |
| More than 1–2 yr before | 5.6 | 3.8 | 0.09 | 4.9 | 5.0 | 0.00 | ||
| More than 2–5 yr before | 10.3 | 7.9 | 0.08 | 9.6 | 9.7 | 0.00 | ||
| More than 5 yr before or never | 70.7 | 83.1 | 0.30 | 77.1 | 77.0 | 0.00 | ||
| Pulmonologist visit in previous year‡ | 26.8 | 2.9 | 0.8 | < 0.001 | 6.5 | 5.7 | 0.03 | 0.004 |
| Internal medicine or geriatrics specialist visits in previous year‡ | 51.0 | 35.2 | 0.3 | < 0.001 | 44.9 | 43.6 | 0.03 | 0.01 |
| Long-term oxygen therapy | 2.9 | 1.5 | 0.1 | < 0.001 | 1.6 | 1.5 | 0.01 | 0.6 |
| General health characteristics | ||||||||
| Primary care physician visits in previous year, median (IQR)‡ | 7 (4–11) | 7 (4–11) | 0.05 | < 0.001 | 7 (4–11) | 6 (4–11) | 0.03 | < 0.001 |
| Influenza vaccination, % | 48.6 | 42.9 | 0.1 | < 0.001 | 45.9 | 46.4 | 0.01 | 0.3 |
| Previous or coexisting medical conditions, % | ||||||||
| Asthma | 29.4 | 19.7 | 0.2 | < 0.001 | 23.5 | 23.5 | 0.00 | 1 |
| Other chronic respiratory disease | 17.5 | 8.2 | 0.3 | < 0.001 | 6.4 | 5.7 | 0.03 | 0.008 |
| Lung cancer | 8.9 | 4.0 | 0.2 | < 0.001 | 11.3 | 10.6 | 0.02 | 0.04 |
| Pulmonary embolism | 2.7 | 2.9 | 0.01 | 0.3 | 2.6 | 2.4 | 0.01 | 0.4 |
| Cor pumonale | 0.1 | 0.0 | 0.02 | 0.007 | 0.1 | 0.0 | 0.01 | 0.3 |
| Acute myocardial infarction | 30.2 | 34.1 | 0.08 | < 0.001 | 30.3 | 30.3 | 0.00 | 0.9 |
| Other ischemic heart disease | 24.7 | 26.8 | 0.05 | < 0.001 | 24.5 | 24.3 | 0.00 | 0.8 |
| Congestive heart failure | 19.6 | 26.4 | 0.2 | < 0.001 | 20.6 | 20.1 | 0.01 | 0.2 |
| Dementia | 5.4 | 15.3 | 0.3 | < 0.001 | 6.2 | 7.2 | 0.04 | < 0.001 |
| Arrhythmias | 21.5 | 25.2 | 0.09 | < 0.001 | 21.7 | 21.1 | 0.02 | 0.2 |
| Cerebrovascular disease | 11.0 | 17.6 | 0.2 | < 0.001 | 12.4 | 12.2 | 0.00 | 0.7 |
| Osteoporosis | 2.2 | 4.2 | 0.1 | < 0.001 | 2.4 | 2.4 | 0.01 | 0.6 |
| Psychiatric disease | ||||||||
| Requiring hospital admission | 0.7 | 1.7 | 0.09 | < 0.001 | 0.9 | 0.9 | 0.00 | 0.8 |
| Requiring ambulatory care visits | 9.3 | 9.5 | 0.01 | 8.9 | 8.9 | 0.00 | ||
| Previous or coexisting medical conditions, % | ||||||||
| None | 90.0 | 88.8 | 0.04 | 90.2 | 90.3 | 0.01 | ||
| Palliative | 1.2 | 2.1 | 0.06 | < 0.001 | 1.3 | 1.3 | 0.00 | 0.7 |
| Overall level of comorbidity§ | ||||||||
| High | 30.4 | 28.4 | 0.04 | < 0.001 | 27.2 | 26.5 | 0.02 | 0.2 |
| Medium | 43.3 | 40.4 | 0.06 | 42.2 | 42.2 | 0.02 | ||
| Low | 26.3 | 31.2 | 0.11 | 30.6 | 31.3 | 0.02 | ||
| Recent acute events, % | ||||||||
| Most recent admission for acute bronchitis, pneumonia or influenza | ||||||||
| In the past 6 mo | 2.4 | 3.2 | 0.05 | < 0.001 | 2.3 | 2.1 | 0.01 | 0.09 |
| > 6 mo before index date | 4.6 | 6.2 | 0.07 | 4.6 | 4.2 | 0.02 | ||
| Never | 93.0 | 90.6 | 0.09 | 93.2 | 93.7 | 0.02 | ||
| Most recent admission for asthma | ||||||||
| In the past 6 mo | 0.5 | 0.2 | 0.05 | < 0.001 | 0.3 | 0.3 | 0.00 | 0.2 |
| > 6 mo before index date | 1.0 | 0.7 | 0.03 | 0.8 | 0.7 | 0.02 | ||
| Never | 98.5 | 99.1 | 0.06 | 98.9 | 99.1 | 0.02 | ||
| Most recent admission for other respiratory disease | ||||||||
| In the past 6 mo | 1.6 | 1.2 | 0.03 | < 0.001 | 0.7 | 0.7 | 0.00 | 0.7 |
| > 6 mo before index date | 2.3 | 1.5 | 0.06 | 1.6 | 1.5 | 0.01 | ||
| Never | 96.1 | 97.2 | 0.06 | 97.8 | 97.9 | 0.01 | ||
| Most recent emergency department visit for acute bronchitis, pneumonia or influenza | ||||||||
| In the past 6 mo | 3.6 | 3.9 | 0.02 | < 0.001 | 3.8 | 3.7 | 0.01 | 0.5 |
| > 6 mo before index date | 8.2 | 7.6 | 0.02 | 8.1 | 7.8 | 0.01 | ||
| Never | 88.2 | 88.4 | 0.01 | 88.1 | 88.5 | 0.01 | ||
| Most recent emergency department visit for asthma | ||||||||
| In the past 6 mo | 1.4 | 0.9 | 0.05 | < 0.001 | 1.3 | 1.2 | 0.01 | 0.9 |
| > 6 mo before index date | 2.8 | 1.9 | 0.06 | 2.4 | 2.4 | 0.00 | ||
| Never | 95.7 | 97.2 | 0.08 | 96.3 | 96.4 | 0.01 | ||
| Most recent emergency department visit for other respiratory disease | ||||||||
| In the past 6 mo | 0.6 | 0.4 | 0.02 | < 0.001 | 0.4 | 0.4 | 0.00 | 0.7 |
| > 6 mo before index date | 0.7 | 0.4 | 0.04 | 0.4 | 0.4 | 0.01 | ||
| Primary care physician characteristics | ||||||||
| Age, yr, mean ± SD | 52.87 ± 10.33 | 53.61 ± 10.23 | 0.07 | < 0.001 | 52.99 ± 10.40 | 53.10 ± 10.19 | 0.01 | 0.3 |
| Women, % | 23.4 | 18.8 | 0.11 | < 0.001 | 21.3 | 21.4 | 0.00 | 0.8 |
| Graduated from a Canadian medical school, % | 75.6 | 76.0 | 0.01 | 0.3 | 75.5 | 75.5 | 0.00 | 1.0 |
| Continuity of care index,¶ median (IQR) | 1 (1–1) | 1 (1–1) | 0.03 | 0.02 | 1 (1–1) | 1 (1–1) | 0.01 | 0.7 |
| Quality of care measures, % | ||||||||
| Glucose testing in previous 3 yr | 88.8 | 83.4 | 0.15 | < 0.001 | 86.5 | 86.6 | 0.00 | 0.8 |
| Cholesterol testing in previous 3 yr | 79.4 | 68.6 | 0.24 | < 0.001 | 76.1 | 76.7 | 0.01 | 0.3 |
Note: COPD = chronic obstructive pulmonary disease, IQR = interquartile range, SD = standard deviation.
↵* Region of province and index year were also considered in propensity score.
↵† Testing the hypothesis of no difference between the groups with and without pulmonary function testing.
↵‡ In Ontario, primary care is provided by family and general practitioner physicians, and specialist COPD care is usually provided by pulmonologists, general internists or geriatricians.
↵§ As indicated by Johns Hopkins Collapsed Ambulatory Diagnostic Groups.21
↵¶ A measure of patients’ access to ambulatory care through the same care provider over time, calculated using the Bice method.22