Association of Clinical Criteria and Computed Tomography Pulmonary Angiogram Findings in Patients Suspected to Have Pulmonary Embolism

Abstract

Background Pulmonary Embolism (PE) is a frequently encountered emergency condition. It brings forth challenges during diagnosis because other conditions can mimic pulmonary embolism. Various diagnostic tools are used for diagnosis including clinical criteria combined with laboratory investigations or diagnostic imaging examinations. Computed Tomography Pulmonary Angiography (CTPA) is a recommended test to confirm diagnosis. Previous studies done in various centers show that the yield of PE from CTPAs done have been unexpectedly low. This means that many patients who undergo these tests end up with a negative outcome, a grave concern considering CTPA exposes the patients to ionizing radiation, extra medical costs and risks of contrast use among other concerns. . Study Objective This study targets to find out the local yield of CTPAs done for pulmonary embolism and correlate the findings of the CTPA with the clinical presentation of the patients using Wells criteria which is a clinical recommended diagnostic tool. Essentially, the study will help to ascertain whether the patients who are sent for CTPA currently actually require the test and if the clinical scoring criteria helps to identify the patients likely to benefit from the test. The study would also seek to find out the overall yield of CTPAs done to negate or confirm the assumption that excessive and unnecessary CTPAs are being done currently. Methodology A prospective analytical study was done at Kenyatta national hospital, radiology department from December 2019 to April 2020. Patients referred to the radiological department for a CTPA study to rule out pulmonary embolism fulfilled the inclusion criteria. These were enrolled into the study. Once enrolled, the demographic information of the patient was taken, then the Wells score was recorded (with the information gathered from patient clerking, primary doctor or the patients hospital file). The CTPA findings were read and findings recorded in the patient’s data collection sheet. All the reported CTPAs were verified by a consultant radiologist before being accepted as part of the study data. Standardized reporting protocol was used in all the cases. Data was analyzed using SPSS version 23, Microsoft Access and Excel it was then represented on tables and graphs. Analysis involved was done to compare the Wells score findings and CTPA for each patient. Significance was defined as p<0.05. Outcome: A total of 103 participants were recruited into the study. Their ages ranged between 17 years and 95 years. The median age was 44.0 years and the mean age 46.2 years. The male: female ratio was 1:2.4. Most of the participants were in the 36 - 45 years age group in both sexes. The patients were derived from emergency department and in patient. The CTPA yield was found to be 34%. The male: female ratio of patients with positive PE on CTPA was 1:1.4. A myriad of additional and alternative diagnosis explaining the symptomatology were found in 86.4 % of the participants. There was no statistically significant difference between the clinical criteria and CTPA findings. Conclusion and Significance of the study: There was a positive correlation of the clinical stratification method used with the radiological findings meaning that the Well’s score can be used with combination with other clinical methods to rule out patients unlikely to benefit from a CTPA. The CTPA yield for PE was 34%, within the recommended level as outline by Royal College of Radiologists and comparable to similar studies in Africa. The knowledge gained will be useful in the development of clinical imaging guidelines for imaging in suspected PE.