Congenital hypothyroidism after assisted reproductive technology in Japan: comparison between multiples and singletons, 2005–2009

Table 2 Concordance rate and RRR of CH, 2005-2009

Multiples			Total ART population		RRR (=A/X)	Japanese general population		RRR (=A/Y)
Concordant	Discordant	Probandwise concordance rate (A)(%)	N	Incidence rate ( ‰) (X)		N	Incidence rate ( ‰) (Y)
pair (N)	pair or set (N)	Probandwise concordance rate (A)(%)	N	Incidence rate ( ‰) (X)		N	Incidence rate ( ‰) (Y)
1	4	33.3	18	0.17	1976	2956	0.55	609

RRR: recurrence risk ratio, CH: congenital hypothyroidism, ART: assisted reproductive technology.
RRR was calculated probandwise concordance rate divided by the incidence rate in the general population.
The incidence rate in the Japanese general population was calculated using the data presented by the Japan Child and Family Research Institute (http://www.boshiaiikukai.jp/img/milk/kensajokyoH22.pdf (In Japanese). Accessed December 23, 2012). The prevalence throughout 2005–2009 was 0.55 ‰ (=2,956/5,398,934).
Probandwise concordance rate was calculated as 33.3%=2/(2+4).
RRR for total ART population was calculated as 1976=(2/6)/(18/106,678).
RRR for Japanese general population was calculated as 609=(2/6)/(2,956/5,398,934).

ISSN: 1687-9856