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Table 1 Association between patient- and physician-level characteristics and having a spinal X-ray or CT/MRI within 6 months after an index visit for non-persistent lower back pain in Alberta between April 1st, 2011 and March 31st, 2012 (N = 97,740)

From: Measuring the frequency and variation of unnecessary care across Canada

 

X-ray

CT/MRI

Characteristic

n

Rate per 100a

Odds Ratio (95% CI)b

Rate per 100a

Odds Ratio (95% CI)b

Patient-level

Age

 18–44 [ref]

49,623

24.6

1.00

3.2

1.00

 45–64

35,736

31.7

1.37 (1.32–1.41)*

5.8

1.66 (1.55–1.77)*

 65–84

11,063

39.8

1.92 (1.83–2.01)*

6.7

1.85 (1.69–2.02)*

 85+

1318

39.9

1.98 (1.76–2.22)*

3.6

0.97 (0.71–1.31)

Sex

 Male [ref]

46,167

29.2

1.00

5.0

1.00

 Female

51,573

29.0

0.96 (0.94–0.99)*

4.2

0.81 (0.76–0.86)*

Income Quintile

 1st – lowest [ref]

21,598

28.6

1.00

3.7

1.00

 2nd

21,028

29.1

1.02 (0.98–1.06)

4.4

1.13 (1.03–1.24)*

 3rd

19,732

29.3

1.03 (0.98–1.07)

4.7

1.15 (1.05–1.26)*

 4th

18,969

29.2

1.03 (0.99–1.08)

4.9

1.19 (1.09–1.31)*

 5th – highest

15,625

30.2

1.05 (1.01–1.10)*

5.3

1.25 (1.14–1.38)*

Rurality

 Urban [ref]

80,951

28.7

1.00

4.1

1.00

 Rural

16,275

31.6

1.05 (0.99–1.10)

7.0

1.38 (1.27–1.49)*

Physician-level

Annual LBP patient volume

 50+ [ref]

54,978

27.2

1.00

3.6

1.00

 50

42,762

31.6

1.16 (1.09–1.22)*

5.8

1.44 (1.30–1.58)*

Specialty

 Specialist [ref]

1018

27.7

1.00

10.3

1.00

 General practitioner

96,722

29.1

1.19 (0.97–1.47)

4.5

0.53 (0.41–0.70)*

Compensation model

 Non-FFS

1878

28.8

1.00

6.1

1.00

 FFS

95,862

29.1

1.21 (1.06–1.37)*

4.5

1.02 (0.81–1.29)

  1. Note: * P ≤ .05; CT/MRI = having either a CT or MRI; CI = confidence interval; LBP = lower back pain; FFS = fee-for-service; [ref] = reference category
  2. arate is the observed imaging rate (# tests/n) at index visit + 6 months for each patient in denominator
  3. bobtained via multivariable regression with adjustments for all patient and physician characteristics listed in table (in addition to patient comorbidity indicator and physician years in practice - both statistically insignificant) using GEEs to account for possible clustering within physicians. Patient comorbidity indicator represented whether patient had history of any of the following comorbidities: coronary artery disease, congestive heart failure, atrial fibrillation, other cardiac arrhythmia, cardiac valvular disease, renal disease, previous cardiovascular disease, peripheral vascular disease, venous thromboembolism, COPD, diabetes, hypertension, and/or asthma