Lung function measurements in children - copsac
Lung function measurements in children - copsac
Lung function measurements in children - copsac
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Material<br />
Study II<br />
Our study group of MZ tw<strong>in</strong>s discordant for severe RSV <strong>in</strong>fection was subgroup of a<br />
larger tw<strong>in</strong> cohort study previously presented by Thomsen et al. (2008) (115).<br />
Four registries were used for recruitment of the study population: The Danish Civil<br />
Registration System (119); The Danish Tw<strong>in</strong> Registry (120, 121); The Danish National<br />
Patient Registry (DNPR) and a research database record<strong>in</strong>g RSV test from all<br />
hospitalizations <strong>in</strong> Denmark (122). The target population was identified by l<strong>in</strong>k<strong>in</strong>g the<br />
personal identification number to 1) the tw<strong>in</strong> status, 2) liv<strong>in</strong>g address and 3)<br />
hospitalizations due to RSV <strong>in</strong>fection dur<strong>in</strong>g the period 1/1-1994 to 31/12-2003. The<br />
registry assured that the control tw<strong>in</strong> had never been hospitalized with RSV <strong>in</strong>fection.<br />
Dur<strong>in</strong>g the period 12,349 tw<strong>in</strong> pairs were born <strong>in</strong> Denmark. Fifty-seven MZ tw<strong>in</strong> pairs<br />
(26 males) were discordant for RSV hospitalization (Figure 9). N<strong>in</strong>e pairs were<br />
unavailable due to death or address protection. Five pairs were excluded based on their<br />
hospital records because the RSV <strong>in</strong>fection was found <strong>in</strong>cidentally dur<strong>in</strong>g<br />
hospitalization for other reasons (i.e. elective surgery) and not associated with lower<br />
respiratory symptoms. Forty-three pairs were <strong>in</strong>vited of which 37 pairs accepted to<br />
participate (14 males; mean age 7.6 years; <strong>in</strong>terquartile range: 5.9-9.2).<br />
The tw<strong>in</strong> status (monozygosity) was confirmed by DNA analysis with 10 highly<br />
polymorphic markers <strong>in</strong> our study population.<br />
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