All eligible UK study members were contacted: 1,918 study members gave information, of which 1,620 study members completed a postal questionnaire and 298 online questionnaire.
| Provided information | 1,918 | ||||||
| Cumulative total of deaths | 1,401 | ||||||
| Cumulative permanent refusals (withdrawn from the study) | 620 | ||||||
| Currently not resident in England, Scotland or Wales (58 completed the postal questionnaire) | 113 | ||||||
| Failure to contact (unable to contact for 10 years) | 857 | ||||||