Open Access Research

Distance saturation product predicts health–related quality of life among sarcoidosis patients

Julie M Bourbonnais, Subramanian Malaisamy, Bhavinkumar D Dalal, Priyan C Samarakoon, Swapna R Parikh and Lobelia Samavati*

Author Affiliations

Department of Medicine, Division of Pulmonary, Critical Care and Sleep, Wayne State University School of Medicine and Detroit Medical Center, Detroit, MI, 48201, USA

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Health and Quality of Life Outcomes 2012, 10:67  doi:10.1186/1477-7525-10-67

Published: 13 June 2012

Abstract

Background

Sarcoidosis is a chronic disease with different phenotypic manifestations. Health-related quality of life is an important aspect in sarcoidosis, yet difficult to measure. The objective of this study was to identify clinical markers predictive of poor quality of life in sarcoidosis patients that can be followed over time and targeted for intervention.

Methods

We assessed the quality of life of 162 patients with confirmed sarcoidosis in a prospective, cross-sectional study using the Sarcoidosis Health Questionnaire (SHQ) and Short Form-36 Health Survey (SF-36). We evaluated the validity of these questionnaires and sought to identify variables that would best explain the performance scores of the patients.

Results

On multivariate regression analyses, the very best composite model to predict total scores from both surveys was a model containing the distance-saturation product and Borg Dyspnea Scale score at the end of a 6-min walk test. This model could better predict SF-36 scores (R2 = 0.33) than SHQ scores (R2 = 0.24). Substitution of distanced walked in 6 min for the distance-saturation product in this model resulted in a lesser ability to predict both scores (R2 = 0.26 for SF-36; R2 = 0.22 for SHQ).

Conclusions

Both the SHQ and SF-36 surveys are valuable tools in the assessment of health-related quality of life in sarcoidosis patients. The best model to predict quality of life among these patients, as determined by regression analyses, included the distance-saturation product and Borg score after the 6-min walk test. Both variables represent easily obtainable clinical parameters that can be followed over time and targeted for intervention.

Keywords:
Sarcoidosis; Health- related quality of life; 6-min walk test; Distance-saturation product