@article {Sumathipala:1 February 2003:1369-0523:67,
	author = "Sumathipala, Athula",
	author = "Siribaddana, Sisira H.",
	author = "Abeysingha, Nihal M.R.",
	author = "De Silva, Nimali",
	author = "Fernando, Devaka J.S.",
	author = "Dayaratne, D.A.R.K.",
	author = "De Silva, Deepthi",
	author = "Warnasuriya, Narada D.",
	author = "Hotopf, Mathew",
	title = "Challenges in Recruiting Older Twins for the Sri Lankan Twin Registry",
	journal = "Twin Research",
	volume = "6",
	year = "1 February 2003",
	abstract = "The National Twin Registry of Sri Lanka was established in 1997 as a volunteer register. To extend it to a population-based register, we examined the effectiveness of tracing older twins by inspecting birth records and recruiting them by postal invitation and in-person contact. Birth records at a divisional secretariat reported from 2 maternity hospitals between the years of 1954-1970 were scrutinised to identify a random sample of twins. These hospitals had the highest twin delivery rates for the whole country. We identified 620 twins and a questionnaire was mailed to them. Research assistants visited a cohort of non-respondents (71) in the postal survey. These 620 twins were identified after perusing 20,700 birth records. The twinning rate was estimated at 29.95 ([620/20700] × 1000) twins per 1000 registered births (CI 27.63-32.27). In the postal survey, 37 (12%) responded and 62 letters were returned (20%). Both twins were still alive in 20 pairs, one was still alive in 15 pairs, and both twins were dead in 2 pairs. During field visits , 42 (59.2%) addresses were located. Information was available on 16 twin pairs. Both twins were alive in 8 pairs, one each in 4 pairs, and both were dead in 4 pairs and at least one twin was traced in 10 pairs (14%). Both the postal and the field survey gave a low yield. This finding is different from tracing younger twins born between 1985-1997 by using the same methods. Migration, urbanization and development in the country might have affected tracing older twins from the birth record addresses, which were decades old.",
	pages = "67-71(5)",
	url = "http://www.ingentaconnect.com/content/aap/twr/2003/00000006/00000001/art00011"
	doi = "doi:10.1375/136905203762687924"
}