The need to accurately measure energy intake and expenditure in patients with systemic sclerosis.

Background: Malnutrition is common in systemic sclerosis and patients are frequently underweight. However, the balance between assessed dietary energy intake versus expenditure has been neglected to date. This study aimed to assess energy (dietary) intakes and expenditures and to compare discrepancies in systemic sclerosis.

Methods: Thirty-six outpatients with systemic sclerosis completed the study. Demographics and clinical data were recorded. Functional questionnaires were completed. Predicted energy requirements were calculated. Over a consecutive 3-day period, patients completed an estimated food diary and wore a specialist energy expenditure monitor (SenseWear^® Armband). Assessments of intake and expenditure were compared for individual patients, and the impact according to patient demographics, clinical manifestations and disease severity evaluated.

Results: Energy intake did not correlate with predicted (s = 0.117; p = 0.511) or measured (s = -0.039; p = 0.825) expenditures. Predicted and measured energy expenditures correlated, but actual values differed for individuals (intraclass correlation = 0.62; 95% limits of agreement = -459 to 751 kcal). Respiratory involvement was negatively correlated with number of steps (s = -0.350; p = 0.04) and time spent lying (s = 0.333; p = 0.05). There was a significant correlation between body mass index and predicted versus measured energy discrepancy (s = 0.41; p = 0.02), and this discrepancy was greater with higher body mass indices.

Conclusion: There was no correlation between intake and either predicted or measured energy expenditure. Predicted and measured energy expenditures were strongly correlated yet differed for the individual patient. In patients with systemic sclerosis, where energy expenditure must be accurately assessed, it should be directly measured.