Table 2. Characteristics of studies reporting sensitivity, stratified by dataset type.

First author, year of publication	Year of study	Country	Study population composition	Age (years)*	Proportion male	Study size (n)	Routine dataset used	Coding system	Codes used to identify cases	Diagnostic coding position	Reference standard
Mortality certificate-derived datasets:
Benito-Leόn 2014[37]	1994–2007	Spain	Three communities near Madrid	Mean 77	56%	82	Mortality	ICD-9 (pre 1999) ICD-10 (post 1999)	Not specified (investigated PD)	Primary	Screening (in-person, telephone and mail questionnaire) and neurological examination
Beyer 2001[38]	1993–1996	Norway	County (Rogaland)	Mean 79	Unclear	84	Mortality	ICD-9 or ICPC	Not specified (investigated PD)	Primary + Any	Semi-structured interview and a clinical examination
Fall 2003[39]	1989–1998	Sweden	Central district of Ӧstergӧtland	Mean 82	Unclear	121	Mortality	ICD-9	Not specified (investigated PD)	Primary + Any	Examination and medical record review
Feldman 2012[24]	1998–2008	Sweden	Twins across Sweden >50yrs	Mean 75	Unclear	PD: 77 Parkinsonism: 127	Mortality	ICD-10	PD: G20 Parkinsonism: G21.4, G21.8, G21.9, G23.1, G23.2, G23.9, G25.9	Any	Screening interview, medical record review and examination
Williams-Gray 2013[40]	2000–2012	UK	County (Cambridgeshire)	Mean 70	Unclear	63	Mortality	Not specified	Not specified (investigated PD)	Primary + Any	History and neurological examination
Hospital-derived datasets:
Feldman 2012[24]	1964–2009	Sweden	Twins across Sweden >50yrs	Mean 75	Unclear	PD: 132 Parkinsonism: 194	Hospital: inpatient	ICD-7 (1961–67) ICD-8 (1968–86) ICD-9 (1987–96) ICD-10 (1997–2009)	PD: ICD-7: 350; ICD-8: 342.00; ICD-9: 332.0; ICD-10: G20 Parkinsonism: ICD-8: 342.08, 342.09; ICD-9: 333.0; ICD-10: G21.4, G21.8, G21.9, G23.1, G23.2, G23.9, G25.9	Any	Screening interview, medical record review and examination

Year of study: the time period during which coded data was collected.

*—any information given regarding the ages of cases or age at recruitment Study size: the total number of true positive according to the reference standard (true positives and false negatives). Where both PD and parkinsonism were investigated in one article, study sizes for both are displayed. Study population composition: population cohort from which cases were identified.

ICD codes for Parkinson’s disease—ICD-7 350; ICD-8 342.00; ICD-9 332.0; ICD-10 G20.

ICD codes for other Parkinsonism—ICD-8: 342.08 (other defined Parkinsonism), 342.09 (unspecified Parkinsonism); ICD-9: 333.0 (other degenerative diseases of the basal ganglia); ICD-10: G21.4 (vascular Parkinsonism), G21.8 (other defined secondary Parkinsonism), G21.9 (unspecified secondary Parkinsonism), G23.1 (progressive supranuclear ophthalmoplegia), G23.2 (striatonigral degeneration), G23.9 (unspecified degenerative disease of basal ganglia), G25.9 (unspecified extrapyramidal and movement disorder).