Table 1.

Description of sample response rates

No. of questionnaires sent out	6367
No. interviews completed and suitable for analysis	4993 (78%)
Interviews not completed or excluded from analysis because of:
Death	42
Not contactable (e.g. change of address)	742
Refusal	76
Excluded because of dementia	4
Excluded because of other serious psychiatric disease	46
Proxy interview only	82
Too many missing items on interview	386
Total interviews not completed or used in analysis	1378 (22%)