In a previous study, we showed that the subjective item assessing cognitive impairment (SSS-Cog) for fibromyalgia (FM) did not correlate with the objective cognitive measures. In the current study, we describe two modifications designed to enhance this correlation: extending the SSS-cog scale from 0-3 to 1-5, and administration of a new questionnaire that specifically targets the cognitive impairments associated with FM.
Sixty-two FM patients underwent a computerised cognitive assessment battery. FM symptoms were assessed on the Fibromyalgia Impact Questionnaire (FIQ); the Widespread Pain Index (WPI); the Symptom Severity Scale (SSS), the new SSS-Cog scale ranging from 1 to 5, the Beck Depression Inventory (BDI) and the new cognitive questionnaire developed by the authors.
Significant correlations were found between the new SSS-Cog, the global cognitive score and all indices [Global Score r=-0.532, p=0.00; Indices: Memory r=-0.305, p=.01; Executive function r=-0.514, p=0.00; Attention r=-0.471, p=0.00; Processing Speed r=-0.468, p=0.00; Motor Skills r=-0.495, p=.00]. Significant correlations were found between the new questionnaire and the global cognitive score and all indices except the memory index [Global Score r=-0.522, p=0.00; Indices: Memory r=-0.163, p=0.212; Executive function r=-0.477, p=0.00; Attention r=-0.439, p=0.00; Processing Speed r=-0.496, p=0.00; Motor Skills r=-0.532, p=0.00].
Given the simplicity involved in extending the scale, we suggest incorporating this modification into the FM diagnostic criteria of the American College of Rheumatology (ACR).