Using Centrally Held Data to Validate Carotid Surgery Outcome Data

Understanding administrative abdominal aortic aneurysm mortality data

OBJECTIVE

Administrative data in the form of Hospital Episode Statistics (HES) and the Scottish Morbidity Record (SMR) have been used to describe surgical activity. These data have also been used to compare outcomes from different hospitals and regions, and to corroborate data submitted to national audits and registries. The aim of this observational study was to examine the completeness and accuracy of administrative data relating to abdominal aortic aneurysm (AAA) repair.

METHODS

Administrative data (SMR-01 returns) from a single health board relating to AAA repair were requested (September 2007 to August 2012). A complete list of validated procedures; termed the reference data set was compiled from all available sources (clinical and administrative). For each patient episode electronic health records were scrutinised to confirm urgency of admission, diagnosis, and operative repair. The 30-day mortality was recorded. The reference data set was used to systematically validate the SMR-01 returns.

RESULTS

The reference data set contained 608 verified procedures. SMR-01 returns identified 2433 episodes of care (1724 patients) in which a discharge diagnosis included AAA. This included 574 operative repairs. There were 34 missing cases (5.6%) from SMR-01 returns; nine of these patients died within 30 days of the index procedure. Omission of these cases made a statistically significant improvement to perceived 30-day mortality (p < .05, chi-square test). If inconsistent SMR-01 data (in terms of ICD-10 and OPCS-4 codes) were excluded only 81.9% of operative repairs were correctly identified and only 30.9% of deaths were captured.

DISCUSSION

The SMR-01 returns contain multiple errors. There also appears to be a systematic bias that reduces apparent 30-day mortality. Using these data alone to describe or compare activity or outcomes must be done with caution.

Evaluation of readmission rates for carotid endarterectomy versus carotid artery stenting in the US Medicare population

OBJECTIVE

We evaluated rates and identified predictors of readmission in the Medicare population after carotid endarterectomy (CEA) compared to carotid artery stenting (CAS).

METHODS

MedPAR data (2005-2009) were used to select patients who underwent CEA or CAS (utilizing International Classification of Diseases, Ninth Revision, Clinical Modification codes). Readmission was evaluated using chi-square and multivariable logistic regression.

RESULTS

A total of 235 247 carotid interventions were performed (211 118 CEA and 24 129 CAS). Readmission rates (%) for patients undergoing CEA and CAS, respectively, were 8.84 and 11.11 (30 days; P < .0001); 13.31 and 17.98 (60 days; P < .0001); and 16.86 and 22.68 (90 days; P < .0001). Patients aged >80 (odds ratio [OR] = 1.25; 95% confidence interval [CI] = 1.20-1.30) and patients with renal failure (OR = 1.6 95%; CI = 1.56-1.73), congestive heart failure (OR = 1.6; 95%CI = 1.57-1.73), diabetes (OR = 1.4; 95% CI 1.27-1.52), and CAS (OR = 1.2; 95%CI = 1.15-1.25) were more likely to be readmitted.

CONCLUSIONS

Interventions for carotid artery disease had high overall readmission rates. After adjustment for comorbidities, utilization of less invasive techniques (CAS) did not result in lower readmission rates. Further evaluation is needed to determine strategies to reduce hospital readmission rates after carotid interventions.