Obesity linked to pain

Obesity is the key public health issue for the 21st century. With around 1 in 5 adults now obese, Australia is experiencing an obesity epidemic. Health professionals are particularly concerned because co-morbidities include coronary heart disease, type 2 diabetes mellitus, hypertension, arthritis and obstructive sleep apnoea. Carrying excess weight can also negatively affect self esteem, sexuality and general well being. Scientists have now added pain to this long list of obesity complications. Although the causal mechanisms remain unclear, it is postulated that obese patients’ quality of life will be improved by weight loss. This article will focus on the association between obesity and the experience of pain.

Cross sectional studies have confirmed an association between obesity and pain. Obesity is defined as having excess body fat, namely a body mass index (BMI) greater than 30. Doctors now recognize three classes of obesity, which reflect the severity of the disease. The worldwide prevalence of obesity continues to increase rapidly, making obesity a serious public health concern. Australia appears to be following the trend of many other developed nations. In 2000, 22.2% of Australian women and 19.3% of men over the age of 25 were obese.¹

Pain can be defined as an "unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage."² It is a symptom associated with many diseases and can vary in severity. Pain may also be classified as acute or chronic, depending on its progression and intensity. The holistic model of pain is now widely accepted among health care professionals. It recognizes that pain has physical, emotional, cognitive, social and spiritual aspects that need to be considered for both pain assessment and management.³

A cross sectional pain prevalence study in the US found that class 1 obese patients were 76% more likely to self-report pain than underweight or normal weight members of the general population. The increased risk of pain was even more significant for class 2 obese patients, suggesting a dose response relationship. Obese patients were also more likely to experience pain in several areas of the body.⁴

Obesity is thought to account for a significant proportion of pain symptoms, including knee pain, osteoarthritis, lower back pain and general musculoskeletal pain.⁵ The mechanisms through which obesity causes pain are not well understood, however, it is thought to result from mechanical and metabolic abnormalities. This is supported by a study of musculoskeletal disorders which showed that increased stress within connective tissue structures caused by excess weight increases the risk of injury. Obesity may also negatively impact soft-tissue structures such as tendon, fascia and cartilage.⁶

Fortunately, quality of life can be dramatically improved for obese patients through weight management. Today doctors are able to employ a range of strategies to actively promote weight loss. Lifestyle adjustments may include encouraging a healthy diet, physical activity and a reduction in alcohol consumption. Meal replacement programs, pharmacotherapy or cognitive behaviour therapy (CBT) may also be suitable. Surgical options such as gastric banding are usually only considered when other interventions have repeatedly failed.

As a health care professional, you are encouraged to remain up to date with emerging research in the field of weight and pain management.

For detailed information on this topic, please see our lifestyle article on obesity and pain.

References:

NHMRC, National clinical guidelines on weight control and obesity management, 2002, NHMRC, Canberra
Jones JB. Pathophysiology of acute pain: Implications for clinical management. Emergency Medicine. 2001;13(3): 288-92.
Hunter New England Area Health Service. Community Information Series: ‘Pain Matters: The Nature of Pain.’ NSW, March 2007.
Hitt H, McMillen R, Thornton-Neaves, Koch K, Corby A. Comorbidity of obesity and pain in a general population: Results from the Southern Pain Prevalence Study. Journal of Pain 2007; 8(5): 430-6.
Janke E. Pain and obesity: Where we have been, where we are going. Journal of Pain 2006; 7(4 suppl 1): S88.
Wearing SC, Henning EM, Byrne NM, Steele JR, Hills AP. Musculoskeletal disorders associated with obesity: a biomechanical perspective. Obesity Reviews 2006; 7(3): 239-50.