Sources of cases and diagnostic criteria used in the included studies
| Study ID | Location | Source of cases | Diagnostic criteria |
|---|---|---|---|
| Asia | |||
| Chen 196820 | Guam | Records of patients attending the Guam Memorial Hospital | Not stated |
| Chang 199423 | Hong Kong, China | Computer search of all major hospitals. Announcement in Hong Kong Medical Association Newsletter asking for information about known or suspected cases. Enquiry of all neurologists and psychiatrists in Hong Kong | All patients examined by a neurologist plus a psychiatrist. Diagnosis based on positive family history plus insidious progressive disorder with chorea, cognitive impairment and often psychiatric disturbance. Positive CT scan with caudate atrophy considered to be ‘supportive’ of an HD diagnosis |
| Chen 201024 | Taiwan | Outpatient and inpatient claims from the National Health Insurance Research Database | Search of National Health Insurance Research Database for ICD-9 code 333.4 |
| Australasia | |||
| McCusker 200031 | NSW, Australia | Records of the NSW HD Service. Records of the major general and chronic psychiatric hospitals in NSW. Questionnaires to adult and paediatric neurologists, psychiatrists, genetic counsellors and clinical geneticists | Definite: chorea or ataxia with a positive family history or expanded CAG repeat |
| Europe | |||
| Palo 198725 | Finland | Systematic search of all university, central, general and central psychiatric hospitals | Not stated |
| Govoni 198827 | Ferrara, Italy | Records of the neurology clinics of Ferrera and Bologna, civil records, records of the psychiatric institutions, records of public and private geriatric nursing homes | Combination of a positive family history, choreiform movements, mental deterioration |
| Ramos-Arroyo 200530 | Navara and Basque, Spain | Referrals to the Medical Genetics Laboratory of the Hospital Virgen del Camino, Pamplona, Spain, for diagnostic testing for HD between 1993 and 2002. Also searched for additional patients from the Basque country who might have been referred to other HD diagnostic genetic centres in Spain. In addition, patients who underwent presymptomatic testing and became symptomatic within the study period were also included | Definite=typical clinical features plus <36 CAG repeats plus positive family history Suspect=without positive family history |
| Mercy 200821 | Cambridge UK | Attendees/referrals to Addenbrooks’ Hospital memory/early dementia clinic | UHDRS >5 |
| Panas 201129 | Greece | Records of the Laboratory of Neurogenetics, Athens (the only neurogenetics lab in Greece) | Neurological examination including the UHDRS plus CAG repeat length in a subset of patients |
| Sackley 201128 | UK | Using THIN primary care research database the authors identified Read codes for HD | Based on recorded diagnosis |
| Sveinsson 201226 | Iceland | Medical records and hospital discharge diagnoses of all hospitals including records of neurological, psychiatric and genetic departments. Information from practising neurologists and selected GPs. Information from family members | Hyperkinetic movement disorder plus psychiatric symptoms plus progressive cognitive decline plus a positive family history or positive DNA analysis |
| Douglas 201322 | UK | Primary care National Health Service electronic health records | As recorded in patients’ electronic health records (Read codes F134.00 and Eu2200) |
| Current study | UK | Primary care National Health Service electronic health records | As recorded in patients’ electronic health records (Read codes F134.00 and Eu2200) |
| North America | |||
| Kokman 199432 | Minnesota, USA | Scrutiny of records of hospitals, nursing homes, private practitioners, state psychiatric hospital | Definite HD=documented record of progressive choreiform movement disorder; evidence of autosomal dominant inheritance; progressive cognitive, behavioural, and/or emotional dysfunction. Probable HD=2 out of 3 of the above criteria |
| Almqvist 200133 | British Columbia, Canada | Patients referred to Medical Genetics Laboratory/HD clinic | Patients with signs and symptoms compatible with HD and with CAG repeat lengths >36 |
HD, Huntington's disease; GP, general practitioner; ICD, International Classification of Diseases; NSW, New South Wales; THIN, The Health Improvement Network; UHDRS, United Huntington's Disease Rating Scale.