Assessing Quality of Life
A consistent finding in pulmonary rehabilitation research has been an improvement in patients’ health-related quality of life. Enhancing quality of life is a central aim of pulmonary rehabilitation programs and is highly valued by patients.
A measure of health-related quality of life should be included in the evaluation of a pulmonary rehabilitation program.
Health-related quality of life can be measured with disease-specific or generic measures. Each form of assessment has its advantages and disadvantages, and there are many examples of each. Due to their widespread and thorough validation, the following questionnaires are recommended:
- Chronic Respiratory Disease Questionnaire (CRDQ or CRQ) – disease specific.
- St George’s Respiratory Questionnaire (SGRQ) – disease specific.
- Medical Outcomes Study Short Form 36 (MOS SF 36) – generic.
Compared to the generic questionnaires, the disease-specific questionnaires are more likely to be responsive to changes after pulmonary rehabilitation and more sensitive to specific respiratory issues. However, the disease-specific questionnaires are also limited by their specificity (i.e. when seeking to compare results to other illness groups).
Compared to the disease-specific questionnaires, the generic questionnaires provide a more global view of the respiratory patient’s quality of life, include a wider range of scales and can be readily compared with other illness groups. However, the generic questionnaires do have lower responsiveness and sensitivity.
The important features of each of these questionnaires are summarised in the table below:
|St. George’s Respiratory Questionnaire (SGRQ)||Chronic Respiratory Disease Questionnaire (CRDQ or CRQ)||Medical Outcomes Study Short Form 36 (MOS SF-36)|
|Practical consider-ations||– 50 items|
– 10-15 minutes
– 20 questions divided into four domains
– 20 questions divided into four domains
– 8-10 minutes
|– 36 items
– 5-10 minutes
– Self- or interviewer- administered
|Domains assessed||– Symptoms (frequency and severity)|
– Impact (social functioning, psychological disturbances)
– Emotional function
– Mastery of disease
Standardized dyspnoea domain available:
1. Feeling emotional, such as angry or upset
2. Taking care of basic needs (bathing, showering, eating or dressing)
4. Performing chores (housework, shopping)
5. Participating in social activities
– Same scoring method for individual/standardized dyspnoea items
– 8 minutes to complete
|– Physical functioning
– Role limitations due to physical health problems
– Bodily pain
– Social functioning
– General mental health
– Role limitations due to emotional problems
– Vitality, energy or fatigue
– General health perceptions
– Ability to calculate a Physical Component and Mental Component score
– Total score can also be calculated from all three components, with 0 indicating no health impairment and 100 representing maximum impairment
– Sensitive and responsive to change after pulmonary rehabilitation
– Measures clinically significant change (a change of 4 U has been identified as the minimum clinically significant change)
– Available in many languages
– Reliability and validity widely tested
– Total score can also be calculated from all four components
– The interviewer administered version is resource intensive
|– Generic measure
– Scores on nine health concepts are transformed linearly to scales of 0 to 100, with 0 indicating maximal impairment and 100 indicating the minimal impairment,
– Validity and reliability widely tested
– Used with many populations
– Good discriminatory potency in interstitial diseases
– A clinically significant change in score has not been determined
– In COPD outpatients, floor and ceiling effects have been noted
– Can compare with other disease groups
Quality of life Questionnaires
When determining the effectiveness of a pulmonary rehabilitation program (see Program Evaluation section), both statistical significance and clinical importance should be considered. The magnitude of change in the scores of some quality of life questionnaires is reflective of an important improvement (e.g. CRDQ, SGRQ). However, with some other instruments (e.g. SF-36), the magnitude of the change that reflects an important improvement has not been determined.
For the SGRQ, a decrease in the score reflects an improvement. The minimum important difference in the SGRQ has been reported to be a change of 4 points for the Total Score.
For the CRDQ, an increase in the score reflects an improvement. The minimum important difference in the CRDQ is 0.5 points per item within each domain. Therefore if all questions within a domain are answered then the clinically important difference for each domain is as follows:
Dyspnoea 2.5 ; Fatigue 2; Emotional Function 3.5; Mastery 2 with the changes for the Dyspnoea and Emotional Function domain often rounded to whole numbers (i.e. 3 and 4 respectively). The magnitude of change in the Total Score for the CRDQ that represents and important difference is 10 points.
Pulmonary rehabilitation has been shown to achieve important and statistically significant in quality of life s using disease specific quality of life questionnaires. The use of generic quality of life questionnaires has detected statistically significant changes in quality of life following pulmonary rehabilitation.