Danish Study Reveals Socioeconomic Disparity in Treatment, Outcomes for NSTEMI, Unstable Angina

Despite the presence of a taxpayer-funded healthcare system in Denmark, social inequality in case fatality is observed in patients with NSTEMI and unstable angina, according to a study published online September 8, 2015, ahead of print in EuroIntervention. Lesser-educated patients wait longer for coronary angiography, but that does not explain the difference in fatality.

Solvej Mårtensson, MSc, PhD, of Glostrup University Hospital (Glostrup, Denmark), and colleagues looked at patients admitted for NSTEMI (n = 16,625) or unstable angina (n = 8,800) in Denmark between 2001 and 2009 at 5 PCI-capable centers and 8 satellite coronary angiography centers. All patients were tracked via the Danish National Patient Registry and sorted by level of education:

• High (10.9%): university, medium-length education, including bachelor’s degrees
• Medium (38.7%): trade/craft education and short-term education
• Low (50.3%): obligatory schooling or high school

Overall, 30% of patients were not invasively examined, 30.1% received coronary angiography but no other invasive treatment, 31.6% underwent PCI, and 8.9% were treated with CABG.

There was a relationship between low education level and increased 30-day and 1-year case fatality, except that 30-day outcomes were no longer related to education level in NSTEMI patients after adjustment for sex, age, preexisting comorbidities, and year of diagnosis (table 1). When angiography was included as a time-dependent covariate, case fatality risk was only slightly attenuated.

NSTEMI patients with low education (adjusted HR 0.78; 95% CI 0.75-0.83) and medium education (adjusted HR 0.88; 95% CI 0.83-0.93) and unstable angina patients with low education (adjusted HR 0.89; 95% CI 0.83-0.96) were less likely than those with higher education to receive coronary angiography within 30 days. However, in those who did receive timely angiography, there were no differences in the likelihood of receiving PCI or CABG within 30 days based on education.

Case fatality after angiography was greater among those with low vs higher education, with no attenuation when time to angiography was factored into the analysis.

Among patients who did not undergo invasive testing, NSTEMI patients in the low-education group had higher 1-year case fatality compared with those with higher education after adjustment.

Inequality Likely Tied to Unobservable Traits

“Overall, our results lead us to believe that the inequality in case fatality is primarily explained by differences in case severity, lifestyle, rehabilitation, adherence to medical treatment, or other factors of health and healthcare that we could not observe—a hypothesis that is consistent with the literature,” write Dr. Mårtensson and colleagues.

But because Denmark has “supposedly equal and easy access to healthcare, it is worrying to find that access to the recommended invasive examination, which is a prerequisite for further invasive treatment, is influenced by the patient’s educational level,” they say. While inequality in access does not seem to affect case fatality, “we cannot exclude that there can be other negative effects on the health and wellbeing of the patients with the lowest educational level.”

It is unclear why those with the lowest education might have longer waiting times for coronary angiography, the authors observe, but it could be that these patients wait longer to go to the hospital and would “therefore have a worse prognosis.”

Future studies should look more closely at why coronary angiography rates might correlate with socioeconomic status, the authors conclude, “and whether this impacts negatively on outcomes other than case fatality.”

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Source: 
Mårtensson S, Gyrd-Hansen D, Prescott E, et al. Does access to invasive examination and treatment influence socioeconomic differences in case fatality for patients admitted for the first time with non-ST-elevation myocardial infarction or unstable angina? EuroIntervention. 2015;Epub ahead of print.

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