Chronic pain: an underestimated cardiovascular risk factor?

Whether epidemiological studies had shown a significant association between pain and the incidence of cardiovascular disorders, several important issues regarding the characters of pain (intensity, duration, localization) and their possible specific cardiovascular outcomes, in association with other risk factors for CVD or individual confounders (such as age, sex etc.) are still undisclosed.

In this large population-based cohort study with approximately half a million participants aged 40–69 years, recruited from across the UK between 2006 and 2010, the investigators expected to explore the association between short-term pain, chronic localized pain and chronic widespread pain (CWP) with the development of CVD, including analyses of those 3 pain categories with specific cardiovascular outcomes such as myocardial infarction, stroke, heart failure and cardiovascular mortality. In addition, they further investigated if those associations are influenced by established cardiovascular risk factors or others variables like sex, age or obesity status and the Population attributable Risk (PAR) for CVD associated with pain was calculated. Most of the baseline data, gathered through self-reported questionnaires, contained information about pain specific characters, demographics, lifestyle, CVD risk factors and common health problems, medication use etc.

During the 7 years of follow-up, increased CVD risk was measured in subjects reporting chronic localized pain (i.e. chronic pain from 1-7 body sites, head, face, neck/shoulder, back, stomach/abdomen, hip or knee for more than 3 months) (HR 1.14, CI 1.08-1.21, p-value < 0.001) and an even stronger risk (HR 1.48, CI 1.28-1.73, p-value < 0.001) was associated with CWP (i.e pain all over the body), compared to those with no pain, after adjustment for physical activity, anxiety, depression, cancer, chronic inflammatory/painful disease, pain/anti-inflammatory medication, socioeconomic status and age completed full education. Individuals with CWP showed the strongest correlation, having a significantly increased risk of cardiovascular death, myocardial infraction and heart failure. PAR for chronic pain (chronic localized pain and CWP together) as risk factors for compound CVD was also important (8.6 %).

Chronic pain, already known as one of the major reasons for disability, is also responsible for major specific CVD outcomes, regardless of underlying pathology, as it was shown in this large population study. It is the pain duration and widespreadness that produced the most important effect to attributable risk for CVD, even in subjects with established CVD risk factors, revealing the need that pain should be further estimated in order to be included to preventive CVD strategies, among the other traditional risk factors.