OBJECTIVE: To investigate whether the Assessment of Motor and Process Skills (AMPS), the physical function subscales of the Fibromyalgia Impact Questionnaire (FIQ PF) and the 36-item Short Form (SF-36 PF) can identify subgroups of women with fibromyalgia with clinically relevant differences in ability to perform activities of daily living.

DESIGN: Cross-sectional study.

SUBJECTS: A total of 257 women with fibromyalgia.

METHODS: Participants were evaluated with the AMPS (measuring activities of daily living motor and activities of daily living process ability), FIQ and SF-36. AMPS independence cut-offs were used to divide the participants into 4 subgroups. Clinically relevant differences between subgroups were investigated based on the AMPS, FIQ PF and SF-36 PF.

RESULT: Participants in the 4 AMPS-derived subgroups demon-strated clinically relevant differences in observed activities of daily living motor and process ability. Neither the FIQ PF nor the SF-36 PF could differentiate between subgroups with clinically relevant differences in AMPS activities of daily living process ability.

CONCLUSION: Activities of daily living process skills reflect underlying organizational and adaptive capacities of the individual and are relevant targets for interventions aiming at improving activities of daily living ability. Since self-report instruments do not capture differences in activities of daily living process ability, clinicians should include observations-based assessment of activities of daily living ability in order to individualize interventions offered.