Fibromyalgia subgroups: profiling distinct subgroups using the Fibromyalgia Impact Questionnaire. A preliminary study

The main goal of this project was to identify the presence of fibromyalgia (FM) subgroups using a simple and frequently used clinical tool, the Fibromyalgia Impact Questionnaire (FIQ). A total of 61 women diagnosed with FM participated in this study. FM subgroups were created by applying a hierarchical cluster analysis on selected items of the FIQ (pain, fatigue, morning tiredness, stiffness, anxiety and depressive symptoms). We also tested for group differences on experimental pain, psychosocial functioning and demographic characteristics. Two cluster profiles best fit our data. FM-Type I was characterized by the lowest levels of anxiety, depressive and morning tiredness symptoms, while FM-Type II was characterized by elevated levels of pain, fatigue, morning tiredness, stiffness, anxiety and depressive symptoms. Both FM subgroups showed hyperalgesic responses to experimental pain. These results suggest that pain and stiffness are universal symptoms of the disorder but that psychological distress is a feature present only in some patients.