Comparison of Three Physician Global Assessment Instruments in Systemic Sclerosis

Physician global assessments (PhyGAs) are variably applied in systemic sclerosis (SSc) clinical trials. The comparability of different PhyGA results is unknown. We sought to assess the comparability of results from three different PhyGA instruments simultaneously applied in the Australian Scleroderma Cohort Study (ASCS).

Using data from 1,965 ASCS participants, we assessed the correlation between results of three PhyGA assessments: (1) overall health, (2) activity, and (3) damage. We evaluated the concordance of change in each PhyGA between study visits. Ordered logistic regression analysis was used to evaluate the clinical associations of each PhyGA.

The absolute scores of each PhyGA were strongly correlated at individual study visits. Concordant changes of the PhyGA scores occurred between 50% of study visits. Only patient-reported breathlessness was associated with all three PhyGA scores (overall health: odds ratio [OR] 1.67, P < 0.01; activity: OR 1.44, P < 0.01; damage: OR 1.32, P < 0.01). Changes in physician-assessed activity scores were also associated with patient-reported worsening skin disease (OR 1.25, P = 0.03) and fecal incontinence (OR 1.23, P = 0.01), whereas damage scores were associated with respiratory disease (pulmonary arterial hypertension: OR 1.25, P = 0.03; chronic obstructive pulmonary disease: OR 1.37, P = 0.04), as well as skin scores (OR 1.02, P < 0.01) and fecal incontinence (OR 1.21, P = 0.02).

PhyGAs of overall health, activity, and damage are each associated with different SSc features, and changes in different PhyGA scores are discordant 50% of the time. Our findings suggest results of variably worded PhyGAs are not directly interchangeable and support the development of a standardized PhyGA.