Subjective Happiness Scale: Measurement properties of the online and paper-pen administrations in Nepali adults with musculoskeletal pain.

Background: Happiness is a positive psychological construct often described as subjective well-being. It is associated with a meaningful life, and better social support and coping with stress or trauma. Happiness may have a role in buffering the negative effects of musculoskeletal pain on quality of life. Validating measures that assess subjective happiness in individuals with musculoskeletal pain can help advance research and patient care in this emerging field.

Objective: We sought to: (1) evaluate the measurement properties of the Subjective Happiness Scale (SHS) in a sample of Nepali adults with musculoskeletal pain; and (2) compare its measurement properties when administered using hard-copy and online methods.

Methods: The Consensus-based Standards for the selection of health status Measurement Instruments (COSMIN) guidelines informed the conduct and reporting. A total of 180 (120 hard-copy and 60 online administrations) individuals with musculoskeletal pain were recruited in Nepal. Content validity, structural validity (exploratory factor analysis), internal consistency (Cronbach's alpha), construct validity (hypothesis testing), and test-retest reliability (Intraclass Correlation Coefficient, ICC_2,1), measurement error were assessed.

Results: Single factor structure of the SHS was supported. The SHS showed good internal consistency for the combined, hard-copy, and online samples (Cronbach's alphas 0.857, 0.848, and 0.847, respectively). It evidenced moderate to good test-retest reliability [ICCs = 0.86 (95 % CI: 0.80, 0.93), 0.89 (95 % CI: 0.82, 0.93), and 0.66 (95 % CI: 0.32, 0.87), respectively]. The findings also supported the construct validity for both administration types.

Conclusions: This study supports the validity of the SHS for assessing subjective happiness in adults with musculoskeletal pain, with moderate to good reliability.