Outcome Measures in Cardiopulmonary Physical Therapy: Focus on the University of California, San Diego Shortness of Breath Questionnaire

Written By: Sam Savage

Published Date: June 28, 2007 Last Edited: June 28, 2007

By Wilson, Christine R

Research Corner INTRODUCTION

Since breathlessness is one of the most limiting symptoms for an individual with cardiac or pulmonary disease, the measurement of dyspnea is a critical component of patient evaluation. Diverse measurement tools have been developed to rate dyspnea in different contexts. For example, the modified Borg1 and Visual Analog ScalesJ are used to assess dyspnea before, during, and after exercise in the clinical laboratory setting. Dyspnea-related questions within the Chronic Respiratory Disease Questionnaire’ provide information about the effect of dyspnea on health related quality of life. The Baseline Dyspnea Index4 assesses dyspnea during activities of daily living. Another tool which can be used to assess dyspnea generated by activities of daily living is the University of California, San Diego Shortness of Breath Questionnaire (UCSD SOBQ). The purpose of this article is to discuss the development, psychometric properties, and usage of the UCSD SOBQ.

DEVELOPMENTAND INTENDED POPULATION

The current UCSD SOBQ is the result of several modifications of a questionnaire described in 1987 by Archibald and Cuidottis which assessed shortness of breath during activities of daily living (ADL) in individuals with chronic obstructive pulmonary disease. Patients were asked to rate dyspnea on a scale of 0-4 (0=absent, 1 =small, 2=moderate, 3=large, 4=severe) at rest, walking, and during ADL.1″1 The scale was adapted for use in the pulmonary rehabilitation program at the University of California, San Diego, and has been used with patients with COPD (including asthma and cystic fibrosis) and post lung transplant. The first modification, described by Eakin et al” in 1995 required patients to rate the frequency of breathlessness during 21 specific activities of daily living (Table 1) and to respond to questions about limitations due to shortness of breath, fear of harm from overexertion and fear of shortness of breath. The frequency rating used a 7 point scale: O (never), 1 (sometimes), 2 (half of the time), 3 (most of the time), 4 (all of the time), 5 (activity given up due to dyspnea), and NA (activity not performed, unrelated to dyspnea). In another modification, described in 1998, the frequency rating scale was changed to a 6 point scale (0=not at all, to 5=maximal or unable to do because of breathlessness).7 Patients are also asked to estimate the degree of shortness of breath anticipated for any listed activities which they do not normally perform. Scores for each question are summed, creating a total score ranging from 0-120 with higher scores indicating more severe breathlessness. The entire UCSD SOBQ can be found in the appendix of the paper by Eakin et al” which addresses validation of the questionnaire.

RELIABILITY

The reliability and validity of the UCSD SOBQ was assessed in 54 individuals (32 male, 22 female) participating in pulmonary rehabilitation.7 Medical conditions included COPD (n=28), cystic fibrosis (n=9), and post lung transplant (n=17). Reliability was determined statistically by assessing internal consistency. The coefficient Cronbach alpha was 0.96, indicating excellent internal consistency, and item-total correlations ranged from 0.49-0.87. In addition, patients were asked to complete both old and new versions of the UCSD SOBQ. The correlation between both versions was 0.96, indicating good agreement.

VALIDITY

Validity was determined in the same group of subjects by comparing UCSD SOBQ scores to other measures.7 The calculated correlations matched the predicted associations. UCSD SOBQ scores were negatively correlated with predicted forced vital capacity (- 0.36) and forced expiratory volume in one second (FEV1 -0.50), diffusion capacity (-0.67), maximal inspiratory pressure (-0.60), health related quality of life (Quality of Well Being questionnaire, -0.41), and the 6 minute walk test (-0.68). Scores were positively correlated with Borg ratings after the 6 minute walk test (0.45), residual volume/total lung capacity (0.47), and depression (Center for Epidemiologic Studies Depression Scale, 0.37).

MINIMAL DETECTABLE CHANCE/RESPONSIVENESS TO CHANGE

This author was not able to find specific mention of the minimal detectable change in the UCSD SOBQ in the literature. However, changes in UCSD SOBQ scores have been correlated with the minimal detectable change in the Transitional Dyspnea Index and are described below under “Responsiveness to Change.” The standard error of the measurement has been reported in a study with 164 subjects with moderate to severe chronic lung disease enrolled in a pulmonary rehabilitation program.8 Statistical data on the baseline UCSD SOBQ in these individuals is: mean 55.5, standard deviation 20.8, standard error of the measurement (SEM) 5.0. SEM was calculated as delta square root (!-reliability coefficient).

Responsiveness to Change

The responsiveness to change was determined by comparing changes in the UCSD SOBQ scores after pulmonary rehabilitation to changes in the Chronic Respiratory Questionnaire-Dyspnea (CRQ-Dyspnea) score and the Transitional Dyspnea Index (TDI).8 Improvement in breathlessness is noted by a decrease in the UCSD SOBQ score or an increase in the CRQ-Dyspnea score. The CRQDyspnea score was moderately correlated (-0.43) with the UCSD SOBQ score. To compare the sensitivity of change in UCSD SOBQ scores, a receiver-operator curve analysis assessed the CRQ-Dyspnea scores and the UCSD SOBQ scores when the change in TDI was 1 unit (the minimum change detectable by patients). This curve indicated that a 4-6 unit decrease in UCSD SOBQ score and a 4-6 unit increase in CRQ-Dyspnea score was associated with a 1 unit improvement in TDI.

Minimally Clinically Important Difference (MCID)

The MCID has been determined by expert consensus and by calculating effect size, SEM, and comparing agreement between UCSD SOBQ and CRQ-Dyspnea and TDI.8 The effect size was 0.48, indicating a moderate effect size. The SEM was 5 units. The receiver-operator curve mentioned in the preceding section indicated that a decrease of about 5 units in the UCSD SOBQ can detect a 1 unit improvement in the TDI with 69% sensitivity and 67% specificity. Individuals who were experienced in using the questionnaire estimated that a change of 5 units was clinically significant. Based on all of these findings, the MCID was determined to be 5 units.

SUGGESTIONS FOR USE IN THE CLINIC

Dyspnea is a symptom which frequently limits physical activity and contributes to the physical deconditioning associated with pulmonary disease. The Borg and VAS scales are useful to assess dyspnea in the midst of physical therapy sessions. However, physical therapists are interested in knowing whether therapeutic intervention is affecting the daily life of the patient. To assess dyspnea during activities of daily living, the UCSD SOBQ can be used during an initial evaluation as a baseline measurement and during re- evaluations to detect change. It can be completed by a patient in about 5 minutes, without the need for an interviewer, however, patients must answer every question before a total score can be calculated. Shown to be reliable and valid when used with individuals with chronic obstructive pulmonary disease and post lung transplant, it has been used successfully in a number of pulmonary rehabilitation studies.915 In clinical settings, therapists can expect that an effective intervention would produce a decrease of 5 points in the UCSD SOBQ score. Use of the UCSD SOBQ could provide physical therapists with valuable information about the effect of dyspnea on the daily activities of their patients and the effect of physical therapy intervention on this symptom.

REFERENCES

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Christine R. Wilson, PT, PhD

Department of Physical Therapy, University of the Pacific, Stockton, CAq

Address correspondence to: Christine R. Wilson, PT, PhD, Department of Physical Therapy, University of the Pacific, 360 7 Pacific Avenue, Stockton, CA 95211, Ph: 209-946-2397 ([email protected]).

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