TABLE 2

Anaemia is associated with COPD morbidity

AnaemiaPolycythaemia
β (95% CI)#p-valueβ (95% CI)#p-value
CAT score1.40 (0.40–2.41)0.006−0.31 (−1.80–1.19)0.69
mMRC dyspnoea score0.28 (0.12–0.44)0.0010.07 (−0.16–0.31)0.55
SGRQ score4.19 (1.86–6.51)<0.0010.49 (−2.95–3.94)0.78
SF-36 general−2.14 (−3.47– −0.81)0.0021.24 (−0.73–3.21)0.22
SF-36 physical function−2.80 (−4.13 – −1.48)<0.0010.40 (−1.57–2.37)0.69
SF-36 mental health−1.47 (−2.92– −0.01)0.048−0.37 (−2.52–1.79)0.74
6MWD m−51.0 (−65.4– −36.6)<0.001−0.2 (−21.4–20.9)0.98
Moderate exacerbations#1.06 (0.76–1.49)0.720.71 (0.41–1.24)0.23
Severe exacerbations#1.63 (1.10–2.40)0.011.24 (0.64–2.38)0.52

Models adjusted for age, sex, ethnicity, education, body mass index, pack-years smoking, smoking status, congestive heart failure, hypertension, diabetes mellitus, chronic kidney disease, % emphysema, forced expiratory volume in 1 s % predicted, and diffusing capacity of the lung for carbon monoxide % predicted. Coefficients and p-values are in comparison to normal haemoglobin. β coefficient units are points for CAT, mMRC, SGRQ, and SF-36 scores, and metres for 6MWD. CAT: COPD Assessment Test; mMRC: modified Medical Research Council Dyspnoea Score; SGRQ: St. George's Respiratory Questionnaire; SF-36: Medical Outcomes Study Short Form 36-item Questionnaire; 6MWD: 6-min walk distance. #: RR (95% CI) for moderate and severe exacerbations.