, new research suggests.
In the analysis of post-MI health data for more than 18,300 Swedish adults, those with moderate pain were 35% more likely to die from any cause during follow-up, compared with those with no pain, and those with extreme pain were more than twice as likely to die.
Furthermore, pain was a stronger predictor of mortality than smoking.
“For a long time, pain has been regarded as merely a symptom of disease rather than a disease” in its own right, Linda Vixner, PT, PhD, of Dalarna University in Falun, Sweden, said in an interview.
Updated definitions of chronic pain in the ICD-11, as well as a recent study using data from the UK Biobank showing that chronic pain is associated with an increased risk of cardiovascular disease, prompted the current study, which looks at the effect of pain on long-term survival after an MI.
“We did not expect that pain would have such a strong impact on the risk of death, and it also surprised us that the risk was more pronounced than that of smoking,” Dr. Vixner said. “Clinicians should consider pain an important cardiovascular risk factor.”
The study was published online in the Journal of the American Heart Association.
‘Experienced pain’ prognostic
The investigators analyzed data from the SWEDEHEART registry of 18,376 patients who had an MI in 2004-2013. The mean age of patients was 62 years and 75% were men. Follow-up time was 8.5 years (median, 3.37).
Self-reported levels of experienced pain according to the EuroQol five-dimension instrument were recorded 12 months after hospital discharge.
Moderate pain was reported by 38.2% of patients and extreme pain by 4.5%.
In the extreme pain category, women were overrepresented (7.5% vs. 3.6% of men), as were current smokers, and patients with diabetes, previous MI, previous stroke, previous percutaneous coronary intervention, non-ST-segment–elevation MI, and any kind of chest pain. Patients classified as physically inactive also were overrepresented in this category.
In addition, those with extreme pain had a higher body mass index and waist circumference 12 months after hospital discharge.
Most (73%) of the 7,889 patients who reported no pain at the 2-month follow-up after MI were also pain-free at the 12-month follow-up, and 65% of those experiencing pain at 2 months were also experiencing pain at 12 months.
There were 1,067 deaths. The adjusted hazard ratio was 1.35 for moderate pain and 2.06 for extreme pain.
As noted, pain was a stronger mortality predictor than smoking: C-statistics for pain were 0.60, and for smoking, 0.55.
“Clinicians managing patients after MI should recognize the need to consider experienced pain as a prognostic factor comparable to persistent smoking and to address this when designing individually adjusted [cardiac rehabilitation] and secondary prevention treatments,” the authors write.
Pain should be assessed at follow-up after MI, they add, and, as Dr. Vixner suggested, it should be “acknowledged as an important risk factor.”