Pain 1 Year After a Myocardial Infarction is Linked to All-Cause Mortality

Patients who experience moderate and extreme pain 1 year after myocardial infarction (MI) have higher mortality than those who do not, according to the Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) study published in the Journal of the American Heart Association.

Researchers used inpatient data—patient characteristics, treatments, and outcomes— from the SWEDEHEART registry and outpatient data—comorbidities, blood pressure, medications, smoking, and lifestyle variables—from the SWEDEHEART Cardiac Rehabilitation registry to compare the association between levels of pain severity 1 year after MI and all-cause mortality. 

They included 18,376 patients (mean age, 62.0 years; 75.5% men) who had been diagnosed with MI at hospital admission and followed for 1 year after hospital discharge. A follow-up questionnaire was completed by the patients at 12-month follow-up which included a self-reported pain assessment entailing 3 levels of pain severity statements: “I have no pain or discomfort,” “I have moderate pain or discomfort,” or “I have extreme pain or discomfort.” The Cox proportional hazards regression model (adjusted for many variables such as age, sex, and smoking status) was utilized to assess the association between all-cause mortality and pain experienced 12 months after hospital stay.

There were a total of 1067 deaths up to 8.5 years after the 12-month follow-up. Of these deaths, 104 were associated with patients who reported extreme pain 12 months after discharge (12.5% of n=834), followed by 543 deaths with moderate pain (7.7% of n=7025), and 420 deaths with no pain (4.0% of n=10517). The hazard ratio (HR) was higher in patients who reported extreme pain 12 months after discharge than those who reported moderate pain (extreme pain, 2.06; 95% CI, 1.63-2.60; vs moderate pain, 1.35; 95% CI, 1.18-1.55; P <.0001).

A sensitivity analysis that utilized the same model—but only adjusted for age and sex—compared all available pain data (n=40963) to the population in the analysis (n=18376). The HR for moderate pain and extreme pain was found to be 1.71 and 3.04, respectively (P <.0001).

Of note, researchers further assessed the all-cause mortality from 1 year after MI by comparing the risk for pain categories with the risk for smoking using Kaplan-Meier curves. The C-statistics for pain were higher than for smoking (pain, 0.60 vs smoking, 0.55), denoting that pain is a stronger indicator of all-cause mortality risk from 1 year after MI than smoking.  

 “Pain 1 year after MI is highly prevalent, and its effect on mortality 1 year after MI was found to be more pronounced than the effect of the more well-known risk factor, smoking,” the researchers wrote.

This article originally appeared on The Cardiology Advisor