St. George's Respiratory Questionnaire has longitudinal construct validity in lymphangioleiomyomatosis

Area of Science:

• Pulmonary Medicine
• Quality of Life Research
• Rare Lung Diseases

Background:

• Lymphangioleiomyomatosis (LAM) is a rare, progressive cystic lung disease.
• LAM significantly impairs health-related quality of life (HRQL), causing shortness of breath and hypoxemia.
• The utility of the St. George's Respiratory Questionnaire (SGRQ) for tracking longitudinal HRQL changes in LAM is not well-established.

Purpose of the Study:

• To evaluate the St. George's Respiratory Questionnaire (SGRQ) as a tool for assessing longitudinal changes in HRQL in patients with LAM.
• To determine the association between SGRQ scores and established clinical measures of LAM severity.

Main Methods:

• Utilized data from the Multicenter International Lymphangioleiomyomatosis Efficacy and Safety of Sirolimus trial.
• Examined correlations between SGRQ scores and four external measures (anchors): FEV1, diffusing capacity, 6-minute walk test distance, and serum VEGF-D.
• Performed longitudinal analyses to assess changes in SGRQ scores alongside changes in anchor values over 12 months.

Main Results:

• SGRQ scores demonstrated significant correlations with most anchor values at baseline, 6 months, and 12 months.
• Longitudinal analyses confirmed that changes in SGRQ scores paralleled changes in all four anchors over time.
• Patients with greater FEV1 improvement at 12 months showed the most substantial improvements in SGRQ total and domain scores.

Conclusions:

• SGRQ scores are significantly associated with key clinical indicators of LAM severity.
• The SGRQ demonstrates sensitivity to longitudinal changes in LAM, particularly when FEV1 is used as the primary indicator.
• These findings support the validity of the SGRQ for assessing HRQL changes over time in patients with LAM.