Table 4 Standardised incidence ratios for chronic obstructive pulmonary diseases in siblings when both siblings were affected by the same subtype of the disease
SubtypeObstructive chronic bronchitisEmphysema
OSIR (95% CI)OSIR (95% CI)
Obstructive chronic bronchitis4484.45 (2.86 to 6.90)495.56 (2.91 to 10.41)
Emphysema455.10 (2.63 to 9.65)1214.22 (5.17 to 35.24)

  • O, observed number of cases; SIR, standardised incidence ratio; CI, confidence interval.

  • 95% CI does not include 1.00.