Objectives To study changes in all cause mortality of patients with diabetes following below knee amputation (BKA) in England from 1998 to 2023; identifying at risk patients. To equip patients and healthcare providers with accurate estimates of serious adverse events including 90-day complications, reoperation, readmission and further lower limb amputation rates.

Design National population based cohort study.

Setting Hospital Episode Statistics database for NHS England linked to ONS mortality records.

Participants 24,711 patients with diabetes who underwent a below knee amputation in England between April 1998 and April 2023.

Main outcome measures Primary outcomes were all cause mortality rate and amputation free survival calculated with Kaplan-Meier curve analyses. Multivariate logistic regression was used to stratify patient variables associated with mortality and/or re-amputation rate. Secondary outcomes included causes of death, re-amputation rates, temporal variation in post BKA mortality and rate of 90-day peri-operative complications and readmission rates.

Results We identified 24,711 BKA on patients with diabetes in the 25-year period. The rate of BKA decreased from 2002 (5.9/100,000; 95% CI 5.6–6.1/100,000) to 2012 (4.4/100,000; 95% CI 4.2 – 4.5/100,000) and plateaued between 2012-2022 (4.3/100,000 in 2022; 95% CI 4.1 – 4.5/100,000). BKA rates were significantly higher in males (6.7/100,000; 95% CI 6.4 – 7/100,000) compared to females (2.0/100,000; 95% CI 1.8 – 2.1/100,000, P<0.05).

The mortality rates following BKA were 4.6% (30 days), 11.3% (90 days), 23.6% (1 year), and 58.2% (5 years). Only 13% of patients survived to 15 years. The commonest causes of death were chromic ischemic heart disease (16.3%), acute myocardial infarction (10.03%) and medical complications of diabetes (9.0%). Cox Proportional Hazard modelling found female patients (HR 1.08; 95% CI 1.05 – 1.12), increasing age (HR 1.79; 95% CI 1.73 – 1.86 in 60-79 year olds), and higher Charlson co-morbidity index (HR 2.60; 95% CI 1.74 – 3.88) were associated with significantly higher risk of mortality.

90-day post operative complications included reoperation (20.7%), myocardial infarction (3.2%), cerebrovascular accident (1.5%), and pulmonary embolus (0.59%). The ipsilateral re-amputation rate was 10.4% (n=2909), and the contralateral amputation rate was 11.4% (n=2304).

The average length of stay was 33 days (IQR 29, 1-152). 23.4% of patients were readmitted to hospital within 90 days.

Conclusions This landmark 25-year England population study has revealed that BKA in patients with diabetes is still associated with high mortality rates, high rate of further amputation and high incidence of significant complications. Nearly a quarter of patients require readmission within 90 days. Severely co-morbid female patients over the age of 60 years have the highest mortality rate and represent an at risk group in need of national intervention.

The authors have declared no competing interest.

This study was funded by BOFAS and RCS.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

All data produced in the present study are available upon reasonable request to the authors