Forecasting COPD hospitalization in the clinic: optimizing the chronic respiratory questionnaire

Figures & data

Table 1 Baseline characteristics

Variable	Mean ± SD/n (%)
n	493
Age (years)	70±9.5
Sex
Male	267 (54.4)
Active smokers (%)	13
BMI	28.6±6.5
PFT data
FEV1% predicted	42.8±16.7
mMRC dyspnea scale	2±1.13
Exacerbations ≥2 previous year	169 (42)
Hospital admission previous year	163 (33)
ADO index (range: 0–14)	8.8±2.1
GOLD risk groups
A	89 (18.0)
B	86 (17.4)
C	66 (13.3)
D	252 (51.1)

Abbreviations: SD, standard deviation; BMI, body mass index; PFT, pulmonary function test; FEV₁, forced expiratory volume in 1 second; mMRC, modified Medical Research Council; ADO, age, dyspnea, obstruction; GOLD, Global initiative for chronic Obstructive Lung Disease.

Table 2 Univariate logistic models predicting hospitalizations

Variable	P-value	Odds ratio (95% CI)	c-statistic	AIC
Male	0.278	1.23 (0.845–1.795)	0.53	626
Age	0.638	0.99 (0.976–1.015)	0.51	630
FEV1% predicted	0.003	0.98 (0.971–0.994)	0.58	608
mMRC	<0.0001	1.71 (1.421–2.076)	0.65	595
Q1: SOB while angry or upset	0.0002	0.79 (0.697–0.894)	0.62	525
Q2: SOB caring for basic needs	<0.0001	0.75 (0.667–0.849)	0.63	595
Q3: SOB walking	<0.0001	0.74 (0.656–0.839)	0.64	586
Q4: SOB performing chores	<0.0001	0.72 (0.641–0.820)	0.65	568
Q5: SOB in social activities	<0.0001	0.73 (0.643–0.833)	0.64	536
Q6: felt frustrated or impatient	0.002	0.80 (0.694–0.923)	0.59	607
Q7: feeling fear or panic with SOB	<0.0001	0.63 (0.553–0.728)	0.67	573
Q8: fatigue	<0.0001	0.76 (0.670–0.871)	0.61	609
Q9: embarrassed by cough or heavy breathing	0.001	0.82 (0.737–0.933)	0.59	616
Q10: confident could deal with illness	<0.0001	0.76 (0.678–0.868)	0.62	608
Q11: energy	<0.0001	0.70 (0.591–0.835)	0.62	607
Q12: feel upset, worried, or depressed	0.0002	0.76 (0.666–0.883)	0.60	600
Q13: felt in control of breathing problems	<0.0001	0.80 (0.723–0.892)	0.61	604
Q14: felt relaxed	0.013	0.85 (0.751–0.968)	0.57	615
Q15: felt low in energy	0.0001	0.75 (0.657–0.871)	0.61	606
Q16: felt discouraged	<0.0001	0.75 (0.655–0.866)	0.61	608
Q17: felt worn out or sluggish	0.0004	0.78 (0.682–0.897)	0.60	605
Q18: happy with personal life	0.0003	0.77 (0.669–0.887)	0.60	608
Q19: felt upset or scared when difficult to get breath	<0.0001	0.65 (0.569–0.745)	0.67	574
Q20: felt restless, tense, or uptight	0.0001	0.76 (0.665–0.877)	0.60	613
CART groups using all variables	<0.0001	1.77 (1.504–2.094)	0.68	548
CART groups using only CRQ-SAS	<0.0001	1.64 (1.434–1.885)	0.70	556
Factor analysis: factor 1	<0.0001	0.72 (0.619–0.852)	0.61	615
Factor analysis: factor 2	<0.0001	0.67 (0.586–0.781)	0.65	590
Factor analysis: factor 3	<0.0001	0.70 (0.605–0.832)	0.62	612
Factor analysis: factor 4	<0.0001	0.64 (0.550–0.745)	0.66	595
Cluster analysis: cluster 1	<0.0001	0.72 (0.619–0.852)	0.61	615
Cluster analysis: cluster 2	<0.0001	0.64 (0.550–0.745)	0.66	590
Cluster analysis: cluster 3	<0.0001	0.70 (0.605–0.832)	0.62	612
Cluster analysis: cluster 4	<0.0001	0.67 (0.586–0.781)	0.65	595

Abbreviations: CI, confidence interval; AIC, Akaike information criterion; FEV₁, forced expiratory volume in 1 second; mMRC, modified Medical Research Council; SOB, shortness of breath; CART, classification and regression tree; CRQ-SAS, Chronic Respiratory Questionnaire Self-Assessment Survey.

Table 3 Stepwise logistic model results

Model	c-statistic	AIC
CART model with only CRQ-SAS variables	0.70	561.522
CART model with all variables*	0.68	551.709

Note:

* CRQ-SAS variables, mMRC dyspnea scale, age, sex, and FEV₁% predicted.

Abbreviations: AIC, Akaike information criterion; CART, classification and regression tree; CRQ-SAS, Chronic Respiratory Questionnaire Self-Assessment Survey; mMRC, modified Medical Research Council; FEV₁, forced expiratory volume in 1 second.

Figure 1 Algorithm proposed to predict hospitalization in patients with COPD.