This study examined how changes in coding practices for sepsis affected reported mortality rates in NHS hospitals in England. Researchers analysed data from over 1 million hospital episodes between 2016 and 2020. They found that new sepsis coding guidelines introduced in April 2017 led to a significant increase in the number of admissions coded primarily for sepsis. This change in coding practices resulted in variations in reported sepsis mortality rates across different hospitals, making it difficult to determine if changes in mortality were due to actual clinical improvements or just changes in coding. The study highlights the need for caution when interpreting sepsis outcomes and suggests that single-centre studies may not provide a complete picture.
Abstract
Objectives
NHS Digital issued new guidance on sepsis coding in April 2017 which was further modified in April 2018. During these timeframes some centres reported increased sepsis associated mortality, whilst others reported reduced mortality, in some cases coincident with specific quality improvement programmes. We hypothesised that changes in reported mortality could not be separated from changes in coding practice.
Methods
Hospital Episode Statistics from the Admitted Patient Care dataset for NHS hospitals in England, from April 2016 to March 2020 were analysed. Admissions of adults with sepsis: an International Classification of Diseases 10 (ICD-10) code associated with the Agency for Healthcare Research and Quality Clinical Classifications Software class ‘Septicaemia (except in labour)’, were assessed. Patient comorbidities were defined by other ICD-10 codes recorded within the admission episode.
Results
1,081,565 hospital episodes with a coded diagnosis of sepsis were studied. After April 2017 there was a significant increase in admission episodes with sepsis coded as the primary reason for admission. There were significant changes in the case-mix of patients with a primary diagnosis of sepsis after April 2017. An analysis of case-mix, hospital and year treated as random effects, defined a small reduction in sepsis associated mortality across England following the first change in coding guidance. No centre specific improvement in outcome could be separated from these random effects.
Conclusion
Changes in sepsis coding practice altered case-mix and case selection, in ways that varied between centres. This was associated with changes in centre-specific sepsis associated mortality, over time. According to the direction of change these may be interpreted either as requiring local investigation for cause or as supporting coincident changes in clinical practice. A whole system analysis showed that centre specific changes in mortality cannot be separated from system-wide changes. Caution is therefore required when interpreting sepsis outcomes in England, particularly when using single centre studies to inform or support guidance or policy.
Authors: Catherine Atkin , Tanya Pankhurst , David McNulty, Ann Keogh , Suzy Gallier , Domenico Pagano , Elizabeth Sapey , Simon Ball
