Table 1.

Collection rate of survey sheets.

Period	CRF Issued, n	CRF Collected and Fixed, n	Collection Rate (%)
Within 7 days	179	179	100
6 months	198	177	99.4
1 year	156	142	100
2 years	128	76	64.4
3 years	51	11	22.9

Abbreviation: CRF, case report form.