Respiratory symptoms and disease characteristics as predictors of pulmonary function abnormalities in patients with rheumatoid arthritis: an observational cohort study

Table 2 Receiver operator characteristics for individual reported pulmonary symptoms to predict the presence of PFT abnormalities

Pulmonary symptom	Any PFT abnormality^a		Restriction^a		Obstruction^a		Impaired diffusion^a
	AUC	95% CI^b	AUC	95% CI^b	AUC	95% CI^b	AUC	95% CI^b
Cough
Frequent^c	0.60	(0.53 to 0.67)^d	-		-		0.61	(0.53 to 0.70)
Morning	0.57	(0.50 to 0.64)	-		0.62	(0.51 to 0.74)	0.65	(0.56 to 0.74)^d
Daytime or night	0.57	(0.50 to 0.66)	-		-		0.59	(0.51 to 0.68)
Chronic^e	-		-		0.62	(0.51 to 0.75)^d	0.61	(0.52 to 0.71)
Phlegm
Frequent^c	-		-		-		0.59	(0.52 to 0.67)
Morning	-		-		-		0.60	(0.52 to 0.70)
Daytime or night	0.57	(0.51 to 0.63)	-		-		0.61	(0.53 to 0.70)
Chronic^e	0.59	(0.53 to 0.67)^d	-		-		0.66	(0.58 to 0.75)^d
Wheezing
Any	0.58	(0.53 to 0.65)	-		0.63	(0.51 to 0.76)^d	0.62	(0.53 to 0.73)^d
Often^f	0.63	(0.56 to 0.71)^d	-		-		-
Breathlessness
Hurrying or walking on incline	0.56	(0.51 to 0.63)	0.66	(0.51 to 0.80)	-		0.60	(0.51 to 0.70)^d
With level walking at own pace	0.57	(0.51 to 0.64)	0.66	(0.51 to 0.81)^d	-		0.59	(0.50 to 0.67)
After 100 yards of level walking	0.60	(0.52 to 0.67)^d			-		-

PFT, pulmonary function test. ^aAreas under the curve (AUCs) are reported only for internally valid models; that is, those in which the 95% confidence interval (CI) did not include 0.5 (uninformative). ^b95% CI obtained with repeated sampling and calculation of the AUC for 1, 000 bootstrap resamples with replacement. ^cDefined as much as four to six times per day, 4 days or more per week. ^dSymptoms selected for inclusion in subsequent multivariable modeling. ^eDefined as on most days for at least 3 consecutive months per year. ^fDefined as on most days or nights.

ISSN: 1478-6362