Table 1.

Details of studies included in the review

Study	Methodology	Unit studied	Age of patients	Type of admission	Method of assessment of causality and preventability	Types of events classified as DRA	Location of study	Period of data collection	Duration of data collection	Number of admissions	Number (%) DRA	$Number (%) PDRA
Bigby 1987 [19]	Prospective medical record review with physician and patientinterview	All wards in a700-bed tertiary teaching hospital	Adults	Unscheduled and emergency admissions	Majority clinical judgement of three reviewers	ADR	Massa-chusetts,USA	1983–1984	1 year	686	66 (9.6)	36 (5.2)
Chan 2001 [21]	Prospective medical record review andpatient and/orrelative interview	Medical wards at a 500-bed public acute care hospital	Adults aged ≥75 years	Acute unplanned admissions	Two reviewers using ‘Hallas criteria’ for causality,severity andpreventability	ADRUnder-treatmentOver-treatmentNon-compliance	Southern Tasmania, Australia	1998	8 weeks	240	45 (18.8)	37 (15.4)
Courtman 1995 [23]	Prospective medical record review by apharmacist	One acute 32-bed medical ward (including20 geriatricbeds)	Patients aged ≥65 years	All admissions	Unknown numberof reviewers used ‘amended Hallas criteria’ for causality and specific criteriafor preventability	ADRUnder-treatmentOver- treatmentNon-compliance	Toronto,Canada	Sep-tember1992 to February 1993	19 weeks	150	46 (30.7)	18 (12.0)
Cunningham1997 [14]	Prospective medical record and nursingrecord review by apharmacist and patient interview	Care of the elderly wards in a number of hospitals	Patients aged ≥65 years	Admissions to care of the elderly wards over a 4-week period for eachhospital	Majority judgement of three independentreviewers using ‘Hallas criteria’ for causality and preventability	ADRUnder-treatmentOver-treatment	Tayside,UK	March to December 1992	10 months	1011	54 (5.3)	43 (4.3)
Dartnell 1996 [22]	Prospective routine pharmacist review of patients, registrarreview of computer record, and selectedmedical records andpatient interview	Whole hospital	Adults	Admissions via Emergency Department lasting > 24 h	Agreement of two reviewers using modified ‘Karch & Lasagna criteria’ for causality, and specific criteriafor preventability	ADRUnder-treatmentOver-treatmentNon-compliance	Melbourne,Australia	Novemberto December1994	30 days	965	55 (5.7)	36 (3.7)
Green 2000 [16]	Prospective medicalrecord review and patient and/or GPinterview, withfollow-up at5 months	Acute medical admissions units in two hospitals	Adults	Random number selection of 200 acute medical admissions	Agreement of two reviewers using ‘Venulet and Ten Hams classification’ and ‘Naranjo’salgorithm’ toassess causality. Assessment of preventabilityunclear	ADR	Liverpool,UK	Unknown	22 weeks	200	15 (7.5)	12 (6.0)
Hallas 1990 [7]	Prospective medical record review andpatient, relative, general practitioner,or nurse interview	Department of Cardiology	Adults	All admissions	Majorityjudgement of four reviewers using ‘Hallas criteria’ for causality andpreventability	ADRUnder-treatmentOver-treatmentNon-compliance	Odense,Denmark	May to June 1988	2 months	NA	NA	NA
Hallas 1990 [9]	As above	General medicalward	As above	As above	As above	As above	As above	March to May 1988	As above	NA	NA	NA
Hallas 1992 [10]	As above	Respiratory ward	As above	As above	As above	As above	As above	1989	As above	NA	NA	NA
Hallas 1991 [11]	As above	Geriatric ward	As above	As above	As above	As above	As above	March toJune 1998	As above	NA	NA	NA
Hallas 1992 [12]	As above	Six medicalwards	As above	As above	As above	As above	As above	March 1988 toMay 1989	As above	1999	212(10.6)	67 (3.4)
Hallas 1993 [13]	As above	General medicaland geriatricward	As above	Unscheduled admissions to medicalservices fromprimary care	Judgement of one reviewer using ‘Hallas criteria’. Sixty cases randomly selectedfor review bythree reviewers	As above	As above	1989	4 months	703	88 (12.5)	25 (3.6)
Howard 2003 [15]	Prospective routine pharmacist review of patients.Pharmacist review ofselected medicalrecords, and patientand GP interview	Medical admissions ward	Adults	Unscheduled admissions from primary care	Majority judgement of three reviewers used ‘modifiedHallas criteria’ for causality and ‘Hepler criteria’for preventability	ADRUnder-treatmentOver-treatmentNon-compliance	Nottingham,UK	January to June 2001	6 months	4093	265 (6.5)178 (4.3)
Lakshmanan1986 [20]	Prospective review of all drug charts,discharge sheets andselected medical records	Medical inpatient services of 769-bed general teaching hospital	Adults	All admissions to medical services	Judgement of one reviewer using guideline criteria for causality and preventability	ADROver-treatment	Ohio, USA	July to August 1984	2 months	834	35 (4.2)	19 (2.3)
Lindley 1992 [17]	Prospective medical and nursing recordreview	Acute geriatric, medical and heart care wardsin a 677-bedteaching hospital	Patients aged ≥ 65 years	Emergency and scheduled admissions from primary care(readmissionsexcluded)	Researcher comparison of symptoms with known ADR profile of drugs, and then verification withconsultant,registrar orresearcher	ADR	Manchester,UK	Unknown	10 weeks	416	26 (6.3)	13 (3.1)
Pirmohamed2004 [18]	Prospective routine pharmacist review ofpatients. Selected medical recordreview and patient, relative or GPinterview byresearch nurse or pharmacist	Medical and surgical wards in two hospitals (excluding obstetrics and gynaecology)	Adults (over 16 years)	All admissions except obstetric and gynaecology patients	Majority judgement of two or three reviewers using ‘Naranjo algorithm’ and ‘Jones method’for causality and ‘Hallas criteria’ for preventability	ADR	Liverpool,UK	November 2001 to April 2002	6 months	18 820	975 (5.2)	687 (3.7)
Raschetti 1999 [24]	Prospective nurse review of A&Erecords and follow-upof medical records ofpatients admitted	700-bed public hospital	Adults (mean age 54.5 years)	All admissions via the emergency department on the first weekof each month	Researcher judgement of causality and preventability	ADRUnder-treatmentOver-treatmentNon-compliance	Milan,Italy	October 1994 to Sep-tember 1995	12 weeks	1833	45 (2.5)	25 (1.4)

DRA, Drug-related admissions; ADR, adverse drug reaction; PDRA, preventable drug-related admission.