Table 2 Prevalence of potential causes for hypercapnic respiratory failure among cases and control participants

Chronic obstructive pulmonary disease

 Frequency (FEV1/FVC < LLN, n/N (%))

21/42 (50%)

11/105 (11%)

 < 0.001

 Post-BD FEV₁ (L, mean (SD))

1.27 (0.52)

2.44 (0.71)

 Post-BD FEV1 (% predicted, mean (SD))

51 (21)

90 (16)

 Post-BD FVC (L, mean (SD))

2.11 (0.59)

3.17 (0.88)

 Post-BD FVC (% predicted, mean (SD))

64 (15)

92 (13)

 FEV1/FVC < 0.7 (n/N (%))

26/42 (62%)

24/105 (23%)

Congestive cardiac failure

 Frequency (NT-proBNP ≥ 100 pmol/L, n/N (%))

9/35 (26%)

1/81 (1%)

 < 0.001

 NT-pro-BNP (pmol/L, mean (SD))

101 (212)

14 (20)

0.003

Obstructive sleep apnea

 Frequency (AHI ≥ 15 events/hour, n/N (%))

7/25 (28%)

24/70 (34%)

0.6

 AHI (mean (SD))

10.3 (8.6)

12.7 (13.2)

0.4

 Oxygen desaturation index (mean (SD))

17.5 (11.2)

15.9 (14.2)

0.6

Respiratory muscle weakness

 Frequency (SNIP_max < LLN, n/N (%))

16/42 (38%)

11/103 (11%)

 < 0.001

 SNIP_max (cmH₂O, mean (SD))

78 (24)

93 (28)

0.002

Opioid use

 Frequency (n (%))

24 (57%)

27 (26%)

 < 0.001

Benzodiazepine use

 Frequency (n (%))

7 (17%)

14 (13%)

0.6