Capturing diagnosis-timing in ICD-coded hospital data: recommendations from the WHO ICD-11 topic advisory group on quality and safety

Abstract

Purpose: To develop a consensus opinion regarding capturing diagnosis-timing in coded hospital data.

Methods: As part of the World Health Organization International Classification of Diseases-11th Revision initiative, the Quality and Safety Topic Advisory Group is charged with enhancing the capture of quality and patient safety information in morbidity data sets. One such feature is a diagnosis-timing flag. The Group has undertaken a narrative literature review, scanned national experiences focusing on countries currently using timing flags, and held a series of meetings to derive formal recommendations regarding diagnosis-timing reporting.

Results: The completeness of diagnosis-timing reporting continues to improve with experience and use; studies indicate that it enhances risk-adjustment and may have a substantial impact on hospital performance estimates, especially for conditions/procedures that involve acutely ill patients. However, studies suggest that its reliability varies, is better for surgical than medical patients (kappa in hip fracture patients of 0.7-1.0 versus kappa in pneumonia of 0.2-0.6) and is dependent on coder training and setting. It may allow simpler and more precise specification of quality indicators.

Conclusions: As the evidence indicates that a diagnosis-timing flag improves the ability of routinely collected, coded hospital data to support outcomes research and the development of quality and safety indicators, the Group recommends that a classification of 'arising after admission' (yes/no), with permitted designations of 'unknown or clinically undetermined', will facilitate coding while providing flexibility when there is uncertainty. Clear coding standards and guidelines with ongoing coder education will be necessary to ensure reliability of the diagnosis-timing flag.

Keywords: condition-onset flag; diagnosis-timing indicators; hospital performance; international classification of diseases; patient safety; present-on-admission flag; world health organization.

Figure 1

Two options of how a diagnosis-timing flag could be included in hospital morbidity data. We describe how a diagnosis-timing flag (classified based on whether a diagnosis ‘arose after admission’) can provide valuable insights into the timing of diagnostic codes using the following scenario: a patient visits the Emergency Department due to severe chest pain and is admitted to hospital with an AMI. The AMI is treated, but the patient suffers a stroke, which extends his or her hospital stay. The patient has diabetes and hypertension on admission. In this scenario, the AMI is the reason for admission because the symptom chest pain is the clinical manifestation of an AMI, which is diagnosed shortly after admission and is coded as diagnosis1. AMI does not arise after admission; consequently the associated diagnosis-timing flag1 to diagnosis1 would equal ‘N’ for ‘No’ (Option 1). Stroke arises during hospitalization (diagnosis2 = stroke; diagnosis-timing flag2 = ‘Y’ = ‘Yes’), whereas both diabetes and hypertension are present-on-admission (diagnosis3 = diabetes, diagnosis-timing flag 3 = ‘N’; diagnosis4 hypertension, diagnosis-timing flag 4 = ‘N’). An alternative format of diagnosis-timing assignment would be to add an extra digit to the diagnostic ICD code, rather than have it be a separate field (Option 2).