A Longitudinal Study of Adverse Drug Effects in Patients with Fibromyalgia

Patrick Lau
Patrick Lau
John Hopkins University

Lau PK, Burmester JK, Berg DL, Mazza JJ, Schmelzer JR, Yale SH.
Clinical Research Center

Research area: Clinical Research 

Background: Fibromyalgia (FM) is a clinical syndrome that includes chronic widespread musculoskeletal pain and other symptoms such as sleep disturbances and depression. Treatment of FM depends on patient symptoms, physician experience and preferences, and knowledge of adverse drug effects (ADEs). This study examined ADEs associated with drugs currently used in clinical practice for treatment of FM.

Methods: We retrospectively examined the records of 250 patients diagnosed with FM by a rheumatologist in 2011-2012 and abstracted data on medications used to treat FM and ADEs at the person-level. The definition of an ADE is an unfavorable and unintended response to a drug. We calculated the proportion of ADEs by drug using the patient as the observation unit, their exposure to the drug, and ADE occurrence, summing across all patients with same drug exposures. Similarly, we developed data at the person-level to allow comparisons of the likelihood of an ADE from FM drugs between patients who had and did not have ADEs to drugs not prescribed for FM prior to their FM diagnosis by a rheumatologist.

Results: Among the drugs prescribed to at least 10 patients, those most frequently associated with ADEs were Milnacipran (40.0%), Pregabalin (29.5%), Duloxetine (25.6%), Celecoxib (25.0%), and Venlafaxine (25.0%). Drugs with the lowest frequencies of ADEs were Diclofenac Epolamine (0.0%), Baclofen (0.0%), Lidocaine (0.0%), Hydrocodone-Acetaminophen (0.0%), and Ibuprofen (0.0%). Our preliminary analyses suggest that patients who experience a prior ADE to a non-FM drug may have a greater risk of experiencing an ADE from FM treatment (38.98% vs. 29.17%, p = 0.15).

Conclusions: Patients with a history of an ADE to a non-FM drug should be closely monitored for ADEs after FM treatment. One consideration for clinicians when prescribing medications to treat FM should be the risk for ADEs, measured roughly in this study with relative frequencies.