Table 3 Comorbidities, Operational Definitions, and Support for Use

Sleep Disorders

ICD-9 codes of:

Insomnia: 307.41, 307.42, 327.00, 327.01, 780.52, v69.4

Sleep disorders are a specific risk factor for increased health seeking in pain populations [29], and associated with higher rates of consulting for low back pain [30]. Poor sleep induces generalized hyperalgesia, increases anxiety, and affects one’s ability to regulate cortisol in response to stress [31,32,33]. Specifically, severity of insomnia has been correlated with pain intensity in patients with chronic musculoskeletal pain [34].

Sleep-related breathing disorders: 320.20, 327.21, 327.22, 327.23, 327.24, 327.25, 327.26, 327.27, 327.29, 768.04, 770.81

Hypersomnias 307.44, 327.10, 327.11, 327.12, 327.13, 327.14, 327.15, 347.00, 347.01, 347.10, 780.54

Circadian rhythm sleep disorders: 327.31, 327.32, 327.33, 327.34, 327.35, 327.36, 327.37, 327.39

Parasomnias: 307.46, 307.47, 327.41, 327.42, 327.43, 227.4, 300.15, 327.44, 327.49, 368.16, 788.36

Sleep-related movement disorders: 327.51, 327.52, 327.53, 327.59, 333.49

Mental Health Disorders

ICD-9 codes of 295.xx, 296.xx, 297.x, 298.x, 300.xx, 301.xx, 307.8x, 308.xx, 309.xx, 311.xx, v11.x, v15.52, v40.9

Mental health disorders have been shown to impact overall pain and function in patients with musculoskeletal disorders. Depression and anxiety in patients with chronic musculoskeletal pain is associated with higher pain and disability levels, as well as a worse health-related quality of life [30]. Mental health comorbidities are associated with development of chronic disease/disorder, higher overall healthcare utilization and consequently higher costs [31], and contribute to overall disability levels. Post-traumatic stress disorder (PTSD) is ICD-9 code 309.81, specifically.

Substance Abuse

ICD-9 codes of 303.xx, 304.xx, 305.xx

Substance use includes unhealthy dependencies on prescription drugs or alcohol as well as personal history of tobacco use. These dependencies can affect outcomes after musculoskeletal pain or injury in many ways. Opiate use is associated with higher rates of medical visits and healthcare utilization [31]. In those who have chronic musculoskeletal disorders and take higher dosages of opioids long term, there is greater overall healthcare utilization and lower rates of return to work or job retention [33]. Significant use of alcohol for pain relief in people who have chronic musculoskeletal pain can affect sleep and depressive symptoms, which ultimately can increase pain levels, not decrease them [34]. In one population of people with chronic non-cancer pain who were taking opioids, risky levels of drinking alcohol were related to poorer pain outcomes [35]. Smoking is adversely related to functional outcomes after injury, independent of the nature or severity of injury [35]. It is an independent risk factor across a variety of populations and conditions [36, 37], and negatively influences healing after orthopaedic surgeries [38]. It has deleterious effects on peak bone mass [39], bone mineral density, [40] bone healing [41], and wound healing [42], as well as many other general complications [30, 43]. Chronic smokers are also at higher risk for developing muscle pain [44].

Tobacco Use

ICD-9 code of V15.82

Smoking is adversely related to functional outcomes after injury, independent of the nature or severity of injury [35]. It is an independent risk factor across a variety of populations and conditions [36, 37, 45]^, and negatively influences healing after orthopaedic surgeries [38, 46]. It has deleterious effects on peak bone mass [39], bone mineral density [40], bone healing [41], and wound healing [42, 47], as well as many other general complications [48]. Chronic smokers are also at higher risk for developing muscle pain [44].

Metabolic Syndromes (obesity, diabetes, etc.)

ICD-9 codes of 249.xx, 250.xx, 255.0, 272.0, 272.2, 272.4, 278.00-278.03, 278.8, v85.30-v85.39, v85.41-v85.45

Metabolic syndromes affect orthopaedic outcomes. Obesity increases the risk for musculoskeletal disease in not only bones and joints, but also soft tissues [49]. In those with obesity related disease, direct healthcare costs, including medication use, inpatient and outpatient visits, are high [50]. Diabetes can adversely affect wound healing, potentially leading to non-healing wounds that cost upwards of $3 billion per year [51].

Chronic Pain

ICD-9 codes of 338.2x, 338.3, 338.4, 729.1, 780.71, 780.79ICD-9 codes of 338.2x, 338.3, 338.4, 729.1, 780.71, 780.79

Chronic pain has been defined as persistent or recurrent pain lasting longer than 3 months [52], and present after orthopaedic surgery [53]. Poor post-surgical outcomes including pain and patient satisfaction have been associated with pre-surgical chronic pain [54]. Fibromyalgia is a condition characterized by widespread body pain, fatigue, poor sleep, and depression. Characteristics of fibromyalgia have been shown to be predictive of poor post-surgical outcomes [55].

Cardiovascular Diseases

ICD-9 codes of 348.2, 401.xx-405.xx, 410.xx-414.xx, 420.xx-429.xx

Cardiovascular conditions are a group of disorders of the heart and blood vessels. Heart disease has been identified as a comorbidity that predicts poor pain outcomes after total knee and total hip arthroplasty [56]. Congestive heart failure has been shown to be a predictor for total hip revision surgery within 12 months of the original total hip arthroplasty [57]. Cardiovascular disease is a preoperative predictor of poor postoperative subjective outcome for lumbar spinal stenosis surgery [58].

Systemic Arthropathies

ICD-9 codes of 099.3, 274.xx, 696.0-696.8, 710.0, 710.2, 711.15, 711.25, 711.35, 711.45, 711.55, 711.65, 711.75, 711.85, 712.15, 712.25, 712.35, 712.85, 712.95, 714.0, 714.1, 714.2, 714.4, 714.89, 716.25, 718.55,719.35, 720.0, 720.81, 720.89, 720.9, 725, 729.0

There are a number of systemic conditions that can cause pain in multiple joints. Some examples of systemic arthropathies are: ankylosing spondylitis, rheumatoid arthritis, psoriatic arthritis, and juvenile rheumatic arthritis. These comorbidities are associated with increased post surgical pain, decreased function, and reduced quality of life [57]. The economic and societal burden of systemic arthropathies is significant. Healthcare expenditures for those with rheumatoid arthritis are over three times greater than those without rheumatoid arthritis. Adjusted for comorbidities, incremental healthcare expenditures are over $2000 annually [59]. Opioid prescriptions for arthritis related pain has dramatically increased [60], which also drive up healthcare costs.