Fibromyalgia has been estimated to affect 12-17% of rheumatoid arthritis patients (1, 2).
This algorithm was created to identify fibromyalgia patients in a population of rheumatoid arthritis patients. The gold standard used for diagnosis of fibromyalgia was that the treating rheumatologist made a clinical diagnosis of fibromyalgia. Rheumatoid arthritis patients were identified by using a previously validated algorithm (3).
Algorithm included the following conditions:
- ICD-9 729.1 (Myalgia and myositis) was coded 2 or more times on two different dates
- text in clinical documentation (provider clinical notes or problem lists) with any of the following terms:
- fibromyalgia
- myofascial pain
- fibrositis
- fibromyositis
- FMS
Problem Lists:
regexp_like(content, '\b(fibromyalgia|myofascial pain|fibrositis|fibromyositis|FMS)\b', 'i')
Other clinical documents:
regexp_like(content, '\b(fibromyalgia|myofascial pain|fibrositis|fibromyositis)\b', 'i')
Note: In some clinician's notes within the Vanderbilt EHR, "FMS" was used in a physical exam template to document the tests of fibromyalgia tender points.
Validation
The above criteria were applied to 75 RA subjects. 73/75 had clinical diagnosis of fibromyalgia made by the treating rheumatologist for positive predictive value of 97.3%.
References
1. Wolfe F, Michaud K. Severe rheumatoid arthritis (RA), worse outcomes, comorbid illness, and sociodemographic disadvantage characterize ra patients with fibromyalgia. J Rheumatol. 2004 Apr 1;31(4):695–700.
2. Pollard LC, Kingsley GH, Choy EH, Scott DL. Fibromyalgic rheumatoid arthritis and disease assessment. Rheumatology. 2010 May 1;49(5):924–8.
3. 1. Carroll RJ, Thompson WK, Eyler AE, Mandelin AM, Cai T, Zink RM, et al. Portability of an algorithm to identify rheumatoid arthritis in electronic health records. J Am Med Inform Assoc JAMIA. 2012 Jun;19(e1):e162–9.