Validation and clinical interpretation of the St George’s respiratory questionnaire for COPD (SGRQ-C) after adaptation to Malaysian language and culture, in patients with COPD

Table 3 Results from tests of scaling properties of Malaysian translated version of the St George’s Respiratory COPD specific Questionnaire

	Symptom	Activity	Impact	SGRQ-CM
Items n	7	13	20	40
Theoretical Range	0–100	0–100	0–100	0–100
Observed range	8.88–100	22.39–100	9.23–90.61	17.59–92.32
At ceiling % (n) ^a	2.1 (3)	4.3 (6)	0	0
At Floor % ^b	0	0	0	0
Item Convergent Validity ^c	0.44–0.79	0.14–0.72	0.13–0.68	__
Scaling Success % ^d	87.5	84.6	80	__
Cronbach’s α Coefficient	0.74	0.70	0.71	0.87
Test-Retest reliability ^e
Mean Difference ^f	−3.02766	−.78737	−1.37505	−1.44755
ICC	0.89	0.85	0.90	0.88

^a Best possible score; ^b Worst possible score; ^c range of correlation between item and their hypothesized scale; ^d Percentage of items correlated higher with the hypothesized subscale than other subscale; ^e test retest was performed on 48 patients; ^f Mean difference in baseline and 2 weeks SGRQ-CM scores; n number, ICC Intraclass correlation coefficient, SGRQ-CM St George’s Respiratory COPD specific Questionnaire Malaysian version

ISSN: 1477-7525