VALIDATION DATA

Cronbach’s α value for all three subscales was 0.88 and values for the medical, behavioral, and psychoemotional subscales were 0.82, 0.72, and 0.84, respectively.

The content validity of the initial 42 items was assessed by an expert panel composed of three nursing professors and five nurses with more than 5 years of clinical experience in rheumatology. The expert panel evaluated whether the 42 items were suitable for assessing arthritis self-management using a three-point scale. In their study, a CVI score of 0.80 or more was considered to indicate good content validity. Five items with a CVI of less than 0.80 were deleted and five overlapping items were deleted on the basis of suggestions of the expert panel. In addition, three items were considered to need modification by more than 80% of the members of the expert panel because of ambiguous wording. The content validity testing resulted in the development of the fi nal 32- item version of the ASMAT.

A pretest with 10 patients was performed to ensure the ASMAT items were understandable and the time taken to complete the assessment was acceptable. It showed that 80% of patients found all 32 items easy to understand, and that the remaining 20% found most items easy to understand, indicating no obvious problems with respect to understandability.

Confirmatory factor analysis indicated that the 32 items of the ASMAT fit the measurement model, and that the interrelated subscale tasks and their individual items were suitable for assessing arthritis self-management.

Accordingly, the construct validity of the ASMAT was found to be well supported. Standardized coefficients were also estimated to verify the measurement model fit, and all 32 items had acceptable standardized coefficients (range: 0.45–0.78).

The authors also examined correlations between ASMAT scores and self efficacy for self-management and functional disability. Their findings showed that scores of self-efficacy for selfmanagement were significantly related to overall ASMAT scores ( r = .55, p < .001) and with all of ASMAT subscale scores. Functional disability scores were also significantly related to overall scores ( r = − .35, p < .001) and all subscale scores.