Interobserver Variability in Interpretation of VQ SPECT and its Impact on Patient Management

Abstract

Background: Pulmonary Embolism (PE) is a major cause of morbidity, mortality and hospitalization. Ventilation Perfusion lung scan (VQ) is a powerful tool in diagnosing PE. It has been noted that there are some variations between highly experienced physicians in interpreting VQ SPECT due to lack of widely accepted reporting guidelines. Aim of the Study: Is to measure the interobserver variability in interpreting VQ scans, and then re-measure it again after applying standardized guidelines. Methods: Two cohorts of patients were included in this study the first included 347 patients and the second 290. Interobserver variability between 4 experienced physicians was measured on the first cohort and re-measured on the second cohort after applying 10 points agreed standardized guidelines. Results: Showed substantial increase in the percentage of agreement between all the physicians after applying the agreed 10 points standardized diagnostic criteria. This was apparent in all the categories with the highest agreement achieved when comparing 2 physicians. Kappa value increased from 0.346 to 0.4665 between the 4 Physicians, from low 0.3 to high 0.4 range between 3 Physicians and from as low as 0.2762 to the maximum of 0.5516 between 2 physicians. Unclassified number decreased between the 2 cohorts from 16.5% to 8% and subsequently decreasing false positive cases from 7.5% to 1.7%. Conclusion: Adherence to reporting guidelines increases the interobserver agreement in interpreting VQ SPECT leading to better patient outcomes and increased referrer confidence in reporting VQ SPECT.