Provider and patient characteristics associated with repeat antinuclear antibody testing within 12 months of previous test and repeat testing after a positive test result
| Characteristic | Any physician, adjusted OR (95% CI)* | Same physician, adjusted OR (95% CI)* | ||
|---|---|---|---|---|
| Repeat testing within 12 mo of previous test | Repeat testing after prior positive test result | Repeat testing within 12 mo of previous test | Repeat testing after prior positive test result | |
| Physicians | ||||
| Family physicians (reference = rheumatologists) | 0.26 (0.22–0.31) | 0.23 (0.20–0.28) | 0.80 (0.64–1.00) | 0.55 (0.44–0.69) |
| Internists (reference = rheumatologists) | 0.59 (0.44–0.79) | 0.58 (0.44–0.76) | 0.63 (0.47–0.85) | 0.66 (0.50–0.87) |
| All other practitioners (reference = rheumatologists) | 0.39 (0.32–0.48) | 0.33 (0.26–0.42) | 0.63 (0.47–0.84) | 0.56 (0.42–0.73) |
| Physician age ≤ 50 year (reference = > 50 yr) | 0.98 (0.88–1.10) | 0.90 (0.79–1.03) | 1.29 (1.15–1.46) | 1.12 (0.97–1.29) |
| Female (reference = male) | 0.93 (0.84–1.03) | 1.05 (0.93–1.19) | 0.95 (0.85–1.07) | 1.10 (0.96–1.27) |
| Academic centre (reference = community practice) | 1.53 (0.87–2.69) | 1.32 (0.83–2.12) | 1.53 (0.94–2.48) | 1.33 (0.89–1.98) |
| International medical school graduate (reference = Canadian medical school graduate) | 0.96 (0.87–1.07) | 0.91 (0.80–1.05) | 0.81 (0.70–0.93) | 0.75 (0.63–0.88) |
| Patients | ||||
| Age | 1.01 (1.00–1.01) | 1.00 (1.00–1.01) | 1.01 (1.01–1.01) | 1.01 (1.00–1.01) |
| Female (reference = male) | 1.29 (1.25–1.34) | 1.82 (1.73–1.91) | 1.29 (1.23–1.36) | 1.83 (1.72–1.94) |
| Income quintile† (reference = 1 lowest) | ||||
| 2 | 1.03 (0.99–1.07) | 1.06 (1.00–1.12) | 1.05 (1.00–1.10) | 1.06 (0.99–1.15) |
| 3 | 1.05 (1.01–1.10) | 1.12 (1.06–1.19) | 1.04 (0.99–1.09) | 1.10 (1.02–1.19) |
| 4 | 1.07 (1.03–1.12) | 1.19 (1.12–1.26) | 1.04 (0.99–1.10) | 1.16 (1.07–1.25) |
| 5 (highest) | 1.08 (1.03–1.12) | 1.17 (1.10–1.25) | 1.02 (0.97–1.07) | 1.10 (1.01–1.19) |
| Urban residence (reference = rural) | 0.93 (0.86–0.99) | 0.96 (0.89–1.05) | 1.01 (0.93–1.09) | 1.03 (0.94–1.13) |
| Connective tissue disease | 2.20 (2.01–2.41) | 4.18 (3.70–4.73) | 3.08 (2.70–3.51) | 5.37 (4.69–6.14) |
| Hospital admission in previous 6 mo | 0.95 (0.89–1.00) | 0.92 (0.83–1.02) | 0.92 (0.84–1.01) | 0.94 (0.80–1.10) |
| Charlson Comorbidity Index score‡ (reference = 0) | ||||
| 1 | 1.17 (1.10–1.25) | 1.14 (1.03–1.26) | 1.20 (1.10–1.30) | 1.18 (1.04–1.34) |
| ≥ 2 | 1.11 (1.02–1.21) | 0.97 (0.86–1.09) | 1.16 (1.05–1.29) | 0.98 (0.85–1.13) |
| Year of index test (reference = 2010) | ||||
| 2008 | 0.24 (0.21–0.28) | 0.19 (0.16–0.24) | 0.27 (0.22–0.32) | 0.23 (0.17–0.30) |
| 2009 | 0.75 (0.71–0.80) | 0.74 (0.67–0.81) | 0.76 (0.70–0.83) | 0.74 (0.65–0.83) |
| 2011 | 1.09 (1.03–1.16) | 1.16 (1.07–1.25) | 1.06 (0.99–1.13) | 1.08 (0.97–1.20) |
| 2012 | 1.17 (1.10–1.26) | 1.31 (1.19–1.44) | 1.12 (1.04–1.21) | 1.20 (1.07–1.34) |
| 2013 | 1.30 (1.22–1.39) | 1.32 (1.21–1.46) | 1.26 (1.16–1.37) | 1.33 (1.17–1.50) |
| 2014 | 1.45 (1.36–1.56) | 1.44 (1.32–1.58) | 1.39 (1.27–1.52) | 1.36 (1.21–1.51) |
| 2015 | 1.70 (1.56–1.86) | 1.68 (1.50–1.88) | 1.79 (1.59–2.01) | 1.80 (1.54–2.09) |
Note: CI = confidence interval, OR = odds ratio.
↵* Adjusted for patient covariates (age, sex, income quintile, urban residence, year of testing, prior hospital admissions, Charlson Comorbidity Index score, testing or diagnosis for connective tissue disease) and physician covariates (specialty, age, sex, international medical graduate, academic setting).
↵† Based on patients’ postal code and census neighbourhood income quintile.
↵‡ With a look-back period of 2 years before the index test.