Measuring outcomes after major abdominal surgery during hospitalization: reliability and validity of the Postoperative Morbidity Survey

Simon J Davies,R Jonathan T Wilson,Victoria Allgar,Simon J Howell,James Francis,Jonathan Dilley

doi:10.1186/2047-0525-2-1

Abstract

BackgroundMeasurement of outcomes after major abdominal surgery has traditionally focused on mortality, however the low incidence in elective surgery makes this measure a poor comparator. The Postoperative Morbidity Survey (POMS) prospectively assesses short-term morbidity, and may have clinical utility both as a core outcome measure in clinical trials and quality of care. The POMS has been shown to be a valid outcome measure in a mixed surgical population, however it has not been studied in patients undergoing major abdominal surgery. This study assessed the inter-rater reliability and validity of the POMS in patients undergoing major abdominal surgery.MethodsPatients undergoing elective major abdominal surgery were visited on postoperative day 1 until discharge by two novice observers who administered the POMS in order to assess inter-rater reliability. Subjects who had previously had the POMS performed prospectively on postoperative days 3 and 5 were identified from a database. The pattern and prevalence of morbidity was analyzed against hospital length of stay (LOS) in order to validate the POMS in this patient group.ResultsFifty one patients were recruited to the inter-rater reliability study giving a total of 263 POMS assessments. Inter-rater reliability showed a 97.7% agreement with a κ coefficient of 0.912 (95% CI: 0.842 to 0.982). On domain analysis percentage agreement was lowest in the gastrointestinal domain (87.5%), whilst correlation was lowest in the wound (κ: 0.04; 95% CI: −1.0 to 1.0) and hematological domains (κ: 0.378; 95% CI: 0.035 to 0.722). All other domains showed at least substantial agreement. POMS assessments were analyzed for postoperative days 3 (n = 258) and 5 (n = 362). The absence or presence of morbidity as measured by the POMS was associated with a hospital LOS of 6 (IQR: 4 to 7) vs. 11 (IQR: 8 to 15) days on postoperative day 3 (P <0.0001), and 7 (IQR: 6 to 10) vs. 13 (IQR: 9 to 19) days on postoperative day 5 (P <0.0001). The presence of any morbidity on postoperative day 5 conferred an odds ratio for a prolonged hospital LOS of 11.9 (95% CI: 5.02 to 11.92).ConclusionsThis study shows that the POMS is both a reliable and valid measure of short-term postoperative morbidity in patients undergoing major abdominal surgery.

Highlights

Measurement of outcomes after major abdominal surgery has traditionally focused on mortality, the low incidence in elective surgery makes this measure a poor comparator
Inter-rater reliability of the individual components of the Postoperative Morbidity Survey (POMS) and the occurrence of any morbidity in any domain was assessed using the κ coefficient, which assesses agreement beyond that expected by chance alone
The absence or presence of morbidity measured by the POMS was associated with a hospital length of stay (LOS) of 6 (IQR: 4 to 7) vs. 11 (IQR: 8 to 15) days when performed on postoperative day 3 (P

Summary

Introduction

Measurement of outcomes after major abdominal surgery has traditionally focused on mortality, the low incidence in elective surgery makes this measure a poor comparator. The Postoperative Morbidity Survey (POMS) prospectively assesses short-term morbidity, and may have clinical utility both as a core outcome measure in clinical trials and quality of care. This study assessed the inter-rater reliability and validity of the POMS in patients undergoing major abdominal surgery. Measurement of patient outcomes after major abdominal surgery has traditionally focused on mortality; the relatively low event rate for the majority of elective surgical procedures makes this a poor discriminator of both the quality of care between institutions and the effectiveness of Morbidity is a more frequent occurrence after major surgery, in the higher risk patient. For each of the nine domains morbidity is recorded on the presence or absence of preset criteria and it appears to accurately describe the pattern and prevalence of morbidity in the postoperative setting

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