Table 4 external sources of data

Narcology Dispensary.

• Registration at the Izhevsk Narcology Dispensary results in an official record of registration.

• Circumstances leading to registration include being arrested for an alcohol-related offence, compulsory referral by a doctor at a polyclinic or hospital, or voluntary registration by self, or the family of a patient.

• Many of those who display hazardous drinking behaviours are registered for treatment at the Narcology service at some point.

Social Security bureau

• This bureau holds official records of any disability benefit of which people are in receipt.

• The list is definitive and exhaustive, since it is the means by which payments are regulated.

• Since the purpose of this list is to control financial payments to citizens, it is believed to be accurate and complete.

• Records are identifiable by name, date of birth and address, allowing reliable record linkage.

• Details include class of disability and date of registration.

• These data can be compared with the questionnaire item on disability registration.

The City of Izhevsk Police database

• This database holds all records of prison stays.

• It is unaffected by bias, since there are no means by which a record can be avoided if a person has spent time in prison.

• Again, records are identifiable by name, date of birth and address, allowing reliable record linkage.

• Presence/absence of a record can be compared with the questionnaire item regarding whether the index has ever spent time in any prison.