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Self-awareness of computed tomography ordering in the emergency department

  • Amjed Kadhim-Saleh (a1), James C. Worrall (a2), Monica Taljaard (a3) (a4), Mathieu Gatien (a2) and Jeffrey J. Perry (a3) (a4)...

Abstract

Objectives

Physician variation in the use of computed tomography (CT) is concerning due to the risks of ionizing radiation, cost, and downstream effects of unnecessary testing. The objectives of this study were to describe variation in CT-ordering rates among emergency physicians (EPs), to measure correlation between perceived and actual CT-ordering rates, to assess attitudes that influence decisions to order imaging tests, and to identify EP attitudes associated with higher CT utilization.

Methods

This study was a retrospective review of imaging and administrative billing records at two emergency department sites of a tertiary care adult teaching hospital. The study also included a cross-sectional survey of EPs at this hospital. We asked physicians about their perceived ordering behaviour, and what factors influenced their decision to order a CT. We examined correlations between perceived and actual CT-ordering rates. We adjusted ordering rates for shift distribution using a logistic regression model and identified outlier physicians whose ordering rate was significantly lower or higher than expected. We used multivariable regression analysis to determine which survey responses predicted higher CT utilization.

Results

During the study period, 59 EPs saw 45,854 patients, and ordered 6,609 CTs — a mean ordering rate of 14.4% (standard deviation (SD)=4.3%). The ordering rate for individual physicians ranged from 5.9% to 25.9%. Of the 59 EPs, 13 EPs were low-ordering outliers; 12 were high-ordering outliers. Forty-five EPs (76.3%) completed the survey. Mean perceived ordering rate was 12.6%, and was weakly correlated with actual ordering (r=0.19, p=0.21). 42 EPs (93.3%) believed they ordered “about the same” or “fewer” CTs than their peers. Of the 17 EPs in the two highest ordering quintiles, only 3 (18%) knew they were high orderers. In the multivariable analysis, higher ordering was associated with increasing strength of response to the following predictors: medico-legal risk (relative risk [RR]=1.18, 95% CI: 1.03–1.21), risk of contrast (RR=1.14, 95% CI: 1.07–1.22), what colleagues would do (RR=1.09, 95% CI: 0.99–1.19), risk of missing a diagnosis (RR=1.08, 95% CI: 0.98–1.21), and patient wishes (RR=1.07, 95% CI: 0.97–1.17).

Conclusions

There is large variation in CT ordering among EPs. Physicians’ self-reported ordering rate correlates poorly with actual ordering. High CT orderers were rarely aware that they ordered more than their colleagues. Higher rates of ordering were observed among physicians who reported increased concern with 1) risk of missing a diagnosis, 2) medico-legal risk, 3) risk of contrast, 4) patient wishes, and 5) what colleagues would do.

Objectifs

Il y a lieu de se préoccuper des différences d’utilisation que font les médecins de la tomodensitométrie (TDM) en raison des risques du rayonnement ionisant, du coût et des effets en aval des examens inutiles. L’étude avait pour objectifs de décrire les différences de taux de demande de TDM chez les urgentologues, de mesurer la corrélation entre les taux perçus et les taux réels de demande de TDM, d’évaluer les attitudes qui influent sur les décisions de demander des examens par imagerie et de cerner les attitudes des urgentologues associées à une utilisation accrue de la TDM.

Méthode

Il s’agit d’un examen rétrospectif de données d’imagerie médicale et de données administratives sur la facturation, relevées dans deux services des urgences d’un hôpital universitaire de soins tertiaires pour adultes. L’étude comprenait également une enquête transversale menée parmi les urgentologues de cet hôpital. Les médecins devaient répondre à des questions portant sur la perception de leur propre comportement à l’égard des demandes de cet examen, et indiquer les facteurs qui influaient sur leur décision de demander une TDM. De notre côté, nous avons établi des corrélations entre les taux perçus et les taux réels de demande de TDM. Par ailleurs, nous avons rajusté les taux de demande pour tenir compte de la répartition des postes à l’aide d’un modèle de régression logistique et nous avons repéré les médecins jugés « aberrants », c’est-à-dire ceux qui avaient des taux de demande significativement plus bas ou plus hauts que le taux prévu. Enfin, nous avons eu recours à une analyse de régression multivariée pour déterminer les réponses dans l’enquête qui se révéleraient des facteurs prévisionnels d’une forte utilisation de la TDM.

Résultats

Durant la période à l’étude, 59 urgentologues ont examiné 45 854 patients et ont demandé 6609 TDM, soit un taux moyen de demande de 14,4 % (écart type [σ]=4,3 %). Le taux de demande par médecin variait de 5,9 % à 25,9 %. Sur les 59 urgentologues, 13 se sont révélés « aberrants » par leur faible taux de demande de TDM, et 12, par leur taux élevé de demande. Quarante-cinq urgentologues (76,3 %) ont participé à l’enquête. Le taux moyen perçu de demande était de 12,6 % et il était en faible corrélation avec le taux réel (r=0,19; p=0,21). Quarante-deux urgentologues (93,3 %) croyaient que leur taux de demande de TDM était comparable ou inférieur à celui de leurs collègues. Sur les 17 urgentologues qui se sont classés dans les deux quintiles supérieurs, 3 (18 %) seulement savaient qu’ils demandaient plus de TDM que les autres. D’après l’analyse multivariée, le taux élevé de demande était associé à une réaction accrue aux facteurs prévisionnels suivants:risque médicolégal (risque relatif [RR]=1,18; IC à 95% : 1,03–1,21), risque lié aux substances de contraste (RR=1,14; IC à 95% : 1,07–1,22), décision présumée des collègues (RR=1,09; IC à 95% : 0,99–1,19), risque de diagnostic passé inaperçu (RR=1,08; IC à 95% : 0,98–1,21) et demande des patients (RR=1,07; IC à 95% : 0,97–1,17).

Conclusions

Le taux de demandes de TDM varie grandement entre les urgentologues. Le taux autodéclaré de demande de TDM par les médecins est en faible corrélation avec le taux de réel de demande. Ceux qui se sont classés dans les quintiles supérieurs étaient rarement conscients du fait qu’ils demandaient cet examen plus souvent que leurs collègues. Enfin, des taux élevés de demande ont été observés parmi les médecins qui se montraient sensibles aux facteurs suivants : 1) risque de diagnostic passé inaperçu; 2) risque médico-légal; 3) risque lié aux substances de contraste; 4) demande des patients; 5) décision présumée des collègues.

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Copyright

Corresponding author

Correspondence to: James Worrall, Department of Emergency Medicine, University of Ottawa, 1053 Carling Avenue, Ottawa ON K1Y 4E9; Email: jaworrall@toh.on.ca

References

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