Table 3:

Results from studies

StudyComparisonImaging typeEvents, n/NOutcome measure, % of patients or rate per 1 000Risk ratio (95% CI)*Effect (95% CI) with adjustment for clustering reported in original study
Intervention groupControl groupIntervention groupControl group
Cluster RCT
Dichotomous outcomes
Dey et al.19Practitioner education v. no interventionLumbar spine radiography158/1 049156/1 13815.1%13.7%1.1 (0.9 to 1.4)Risk difference 1.4% (−4.1% to 6.8%)
Schectman et al.20Audit + feedback v. no interventionLumbar spine radiography112/58898/54419.0%18.0%1.1 (0.8 to 1.4)Not reported
Lumbar spine CT or MRI33/58839/5445.6%7.1%0.8 (0.5 to 1.2)Not reported
French et al.18Practitioner education v. guideline disseminationLumbar spine radiography643/77 716768/75 2268.3 per 1 00010.2 per 1 0000.8 (0.7 to 0.9)IRR 0.8 (0.6 to 1.1)
Lumbar spine CT474/77 716496/75 2266.1 per 1 0006.6 per 1 0000.9 (0.8 to 1.1)IRR 0.9 (0.7 to 1.3)
Eccles et al.7Audit + feedback v. guideline disseminationLumbar spine radiographyNRNR6.0 per 1 0006.8 per 1 0000.9 (NC)Absolute change in rate −0.07 (−1.3 to 0.9)
Reminders v. guideline disseminationLumbar spine radiographyNRNR5.1 per 1 0006.8 per 1 0000.8 (NC)Absolute change in rate −1.5 (−2.5 to −0.6)
Reminders + audit + feedback v. guideline disseminationLumbar spine radiographyNRNR5.2 per 1 0006.8 per 1 0000.8 (NC)No effect (no numeric data reported)
Continuous outcomes
Kerry et al.21Audit + feedback v. no interventionNRNRPercentage mean difference§ in change score: −20% (3% to 37%)
StudyInterventionMean no. of referrals per month before interventionAbsolute change in referrals in first month after intervention (95% CI)§Change in slope of linear trend line from before to after intervention (95% CI)
Interrupted time series
Matowe et al.17Guideline dissemination147.7−7.7 (−24.7 to 40.2)0.0 (−1.8 to 1.8)
Baker et al.24Clinical decision support120.3−44.3 (−48.7 to −39.9)2.0 (−2.1 to 6.1)
  • Note: CI = confidence interval, CT = computed tomography, IRR = incident rate ratio, MRI = magnetic resonance imaging, NC = not calculated because of lack of data presented in original study, NR = not reported, RCT = randomized controlled trial.

  • * Analysis based on extracted raw data, not adjusted for clustering.

  • Value less than 1 represents a decrease in imaging in the intervention group compared with the control.

  • § Negative value represents a decrease in imaging in the intervention group compared with the control.

  • Positive value indicates a sustained effect of the intervention over time.

  • Time series regression analysis.