The Development of a COPD Exacerbation Recognition Tool (CERT) to Help Patients Recognize When to Seek Medical Advice

Figures & data

Table 1 Patient Demographics

Demographic	Step 1	Step 3
Age, (years), mean	69	69
Smoking status (%)
Current	27	35
Ex-smokers	46	42
Never smokers	27
Missing data		23
FEV1 (% predicted), mean	59	63
CAT score, mean	19	15
Exacerbation frequency in previous year (median)
Moderate	2	2
Hospitalized	1	2
Education level (%)*
Primary school	35	27
Middle school	44	48
College or above	10	17
Illiterate	10	9

Notes: *Sum may be greater than 100% due to rounding.

Abbreviations: CAT, Chronic Obstructive Pulmonary Disease Assessment Test; FEV₁, forced expiratory volume in 1 second.

Figure 1 Response rates (moderate and severe combined) for severity score and change score.

Table 2 Factor Loadings from an Exploratory Factor Analysis Using Moderate and Severe Responses to Severity of Item During an Exacerbation (Severity Score) or Moderate and Severe Responses to the Change in Item from the Normal State (Change Score)

Items	Severity Score		Change Score
	Factor 1^#	Factor 2^#	Factor 1^#	Factor 2^#
Factor Loading
Item 1. Appearance of purulent/thick sputum	0.19	0.55*	0.21	0.52*
Item 3. Worsening of cough	0.14	0.60*	0.23	0.66*
Item 5. Hard to cough out sputum	0.23	0.36	0.25	0.42
Item 7. Colour of sputum changes	0.16	0.67*	0.15	0.65*
Item 8. Volume of sputum increased	0.11	0.68*	0.14	0.78*
Item 9. Abnormal sound during breathing/wheezing	0.49*	0.34	0.52*	0.37
Item 10. Laborious breathing	0.79*	0.13	0.81*	0.21
Item 11. Shortness of breath	0.74*	0.19	0.77*	0.17
Item 12. Chest distress	0.60*	0.27	0.65*	0.23
Item 13. Limitation of motion	0.77*	0.16	0.77*	0.21
Item 15. Exhaustion & fatigue	0.71*	0.17	0.66*	0.25
Eigen values	8.31	2.19	10.16	2.52
Proportion (%)	79.1	20.9	80.1	19.9
Cumulative (%)	79.1	100.0	80.1	100.0

Notes: ^#The factor loadings are from the varimax rotation factor pattern. *Indicates items that are significantly associated with the factors.

Table 3 Mean Factor Loadings and Mean Response Rates for the 11 Highest Responded Items Combining Data from Both Response Formats (Severity During the Exacerbation and Severity of Change from the Usual State)

	Mean Factor Loading	Mean Response Rate n (%)
Factor 1
Item 10. Laborious breathing	0.80	89 (59)
Item 13. Limitation of motion	0.77	84 (56)
Item 11. Shortness of breath	0.76	92 (61)
Item 15 Exhaustion & fatigue	0.69	74 (49)
Item 12. Chest distress	0.63	70 (47)
Item 9. Abnormal sound during breathing (wheezing)	0.51	73 (49)
Factor 2
Item 8. Volume of sputum increased	0.73	93 (62)
Item 7. Color of sputum changes	0.66	58 (39)
Item 3. Worsening of cough	0.63	98 (65)
Item 1. Appearance of purulent/thick sputum	0.54	85 (57)

Figure 2 Item loading using responses to severity score and change score: (A) Factor 1, (B) Factor 2. *Indicates significant loading.