Long-Term Prognosis After Elective Abdominal Aortic Aneurysm Repair Is Poor in Women and Men

The Challenges Remain

Ruth M. A. Bulder, Bsc; Mareia Talvitie, MD; Esther Bastiaannet, PhD; Jaap F. Hamming, MD, PhD; Rebecka Hultgren, MD, PhD; Jan H. N. Lindeman, MD, PhD

Disclosures

Annals of Surgery. 2020;272(5):773-778. 

In This Article

Methods

Ethical Approval

This study was approved by the Regional Ethics Review Board in Stockholm and complies with the Declaration of Helsinki. For this population-based study, informed consent was not required, and the handling of data fulfils the requirements of the EU data protection laws.

Registry Data

All persons in Sweden are registered with an individual person-specific identity number, which allows merging data on an individual-level from different national registries.[13] The Swedish National Patient Registry (NPR) covers all hospital-associated care events and outpatient specialist care events based on the person-specific identity numbers in Sweden, a country with 9.8 million inhabitants in 2015. The NPR has a positive predictive value up to 96%.[11] All Swedish patients who underwent elective infrarenal AAA repair between 2001 and 2015 in 1 of the 30 hospitals that provide elective repair were identified through the Swedish NPR and the Cause of Death Registry.[12]

Data extraction was based on the first registered diagnosis (intact AAA, International Classification of Diseases-9 (ICD-9), and ICD-10 codes). This study only includes patients with elective AAA repair, patients with a diagnosis of ruptured AAA were excluded. Comorbidities included all registered diagnoses in the 5 years before the diagnosis AAA. Evaluated comorbidities were hypertension, hyperlipidaemia, heart disease, peripheral artery disease, stroke, chronic obstructive pulmonary disease, renal disease, diabetes, dementia, and thoracic aneurysm (IDC-9 and ICD-10 codes are provided in the Supplemental Table 1). Survival data were cross-matched with the Cause of Death Registry until December 31, 2016.

Time-resolved Analysis

To explore the possible impact of changes in AAA management over time, that is, the implementation of EVAR and intensified CVDRM, 3 different time frames, based on the proportion patients treated with OR versus EVAR, were defined and compared (see results).

Outcome Measures

The primary outcome was relative survival, which is the preferred method for estimating disease-specific outcomes in a population-based setting.[14–17] Relative survival analyses provide the opportunity to (1) quantify AAA-associated excess mortality and (2) to adjust for changes in life-expectancy (ie, an altered age and sex distribution) due to demographic alterations over time.

Secondary outcome measures included short-term mortality and cause of death.

Statistical Analysis

All analyses were performed with Stata/SE, version 12.0 (StataCorp, College Station, TX). Normality was assessed by histograms. Continuous variables were expressed as means (+SD) or medians (+IQR) and compared using Student t-test or Mann-Whitney test. Categorical data were analyzed using the Chi-square test. A 2-sided P-value of <0.05 was considered statistically significant.

Relative survival was calculated by dividing the observed survival of the study population (ie, electively treated AAA patients) and the expected survival of a general population (ie, Swedish population) matched for age-, sex-, and year of operation.[18] Expected survival was retrieved from population life-tables.[19] A relative survival below 1 indicates that the survival of the study cohort is lower than expected on basis of the reference population.

Cox regression analysis was used to identify factors associated with 90-day and overall mortality. Each variable was tested for significance (P < 0.1) in a univariate analysis before entering into the multivariate model. Result are presented as hazard ratio (HR) and 95% confidence intervals (CIs).

A sensitivity analysis to address a possible impact of changes in patient frailty over time was performed by progressively excluding octogenarians from period 3 and determining the effect on the relative survival.

This study was conducted according to the STROBE guidelines for reporting of observational cohort studies in epidemiology.[20]

Comments

3090D553-9492-4563-8681-AD288FA52ACE

processing....