Lung function measurements in children - copsac

Material
Study II
Our study group of MZ twins discordant for severe RSV infection was subgroup of a
larger twin cohort study previously presented by Thomsen et al. (2008) (115).
Four registries were used for recruitment of the study population: The Danish Civil
Registration System (119); The Danish Twin Registry (120, 121); The Danish National
Patient Registry (DNPR) and a research database recording RSV test from all
hospitalizations in Denmark (122). The target population was identified by linking the
personal identification number to 1) the twin status, 2) living address and 3)
hospitalizations due to RSV infection during the period 1/1-1994 to 31/12-2003. The
registry assured that the control twin had never been hospitalized with RSV infection.
During the period 12,349 twin pairs were born in Denmark. Fifty-seven MZ twin pairs
(26 males) were discordant for RSV hospitalization (Figure 9). Nine pairs were
unavailable due to death or address protection. Five pairs were excluded based on their
hospital records because the RSV infection was found incidentally during
hospitalization for other reasons (i.e. elective surgery) and not associated with lower
respiratory symptoms. Forty-three pairs were invited of which 37 pairs accepted to
participate (14 males; mean age 7.6 years; interquartile range: 5.9-9.2).
The twin status (monozygosity) was confirmed by DNA analysis with 10 highly
polymorphic markers in our study population.
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