Table 1.

Summary of the included studies and quality assessment results.

Authors	Settings	Study period	Sample size	Study design	Risk factors identified	NHMRC Level of evidencea	MMAT Scoring b
Ab Fatah et al, 201744	Teaching hospital, Malaysia	7 weeks	144	Case-control	Female sex, currently taking medication, comorbidity, a history of drug allergy and recent hospital admission	III-3	4
Salvi et al., 201717	Geriatric hospital, Italy	6 months	4042	Observational cohort study	Polypharmacy	IV	5
Chen et al., 201518	General Hospital, Taiwan	12 months	452	Prospective cohort study	Older population ⩾65 years	II	5
De Pepe et al., 201319	University hospital, Belgium	3 weeks	87	Prospective cohort study	Number of medications and age	II	3
Perrone et al., 201420	16 General hospitals, Italy	24 months	8862	Retrospective cohort study	Older age, Yellow and Red triage, number of medications, previous ED visit for the same ADE	III-2	3
Chen et al., 201421	Tertiary medical center, Taiwan	12 months	20,628	Case-control	Number of medications and increased serum creatinine.	III-3	4
Asseray et al., 201322	11 French academic hospitals, France	8-week period	3027	Prospective observational study	Age, gender, use of nervous system drugs, polypharmacy	II	4
Roulet et al., 201323	Tertiary care hospital, France	2 months	433	Cross sectional	Involuntary intoxication, hospitalized patients, poly-pathological condition, endocrine pathology and daily prescription of CVS drugs	IV	5
Pedros et al., 201351	Tertiary medical center, Spain	120 days	4098	Cross sectional	Old age and number of medications	IV	4
Nickel et al., 201324	University hospital, Basel, Switzerland	24 months	633	Cross-sectional	Comorbidities and number of medications	IV	4
Castro et al., 2013 52	University hospital, Barcelona, Spain	3 months	652	Cross-sectional study	Number of medications taken	IV	3
Heaton et al., 201225	NHAMCS, US	3 years	456,209	Retrospective cohort study	Mental illness, type II diabetes, nondependent abuse of drug and essential hypertension	III-2	4
Jayarama et al., 201226	Tertiary hospital, Kola, India	12 months	133	Prospective observational studies	Comorbidity, multiple prescribers, visiting many pharmacies and number of medications	II	3
Chen et al., 201275	Academic hospital, Taiwan	12 months	452	Prospective cohort study	Elderly age, severity of ADE, higher Charlson comorbidity index scores	II	4
Wu et al., 201227	Ontario, Canada	5 years		Retrospective cohort study	Female gender, old age, comorbidity, Number of medications, newly prescribed drugs, recent ED visit, multiple-pharmacies, recent -admission, and long-term care	III-2	4
Marcum et al., 201253	152 Veterans Affairs Medical Centers US	NR	778	Retrospective cohort study	Polypharmacy	III-2	4
Hohl et al., 20118	2 Tertiary hospitals. Vancouver, Canada	6 months	1591	Prospective observational studies	Comorbidity, antibiotic use within 7 days, medication changes within 28 days, age 80 years, arrival by ambulance, triage acuity, recent hospital admission, renal failure, and use of three or more prescription medications	II	5
Harduar-Morano, et al., 201128	Florida AHCA	NR	3024	Retrospective cohort study	Old age, white patients, and female gender	III-2	3
Vila-de-Muga et al, 201129	Academic tertiary care children’s hospital	1 week	1906	Retrospective cohort study	ED shift on weekends, holidays and between 0000 and 0800 hours	III-2	3
Perron et al., 201130	NESARC, US	NR	43,093	Retrospective cohort study of survey database	Heroine, inhalant and marijuana dependence. Pyschopathological factors: personality and mood disorder, socially connected has a protective factor	III-2	3
Budnitz et al., 201131	NEISS-CADES US	2 years	177,504	Retrospective cohort study	Drugs with narrow therapeutic index; digoxin, insulin and warfarin	III-2	4
Braden et al., 200232	HealthCore and Arkansas Medicaid, US	NR	48,650	Retrospective cohort study	Use of short acting Drug Enforcement Agency Schedule II opioids	III-2	3
Sikdar et al., 201133	Two tertiary hospitals, Canada	12 months	1458	Retrospective chart review	Comorbidities and number of medications.	III-2	5
Ramos et al., 201034	University hospital, Spain	3 months	888	Cross sectional study	Number of drugs, female gender and health practice index	IV	4
Maria et al., 201035	3 hospitals, Italy	3 years	2644	Cross-sectional	Comorbidity, multiple drug regimens	IV	3
Backmund et al., 200936	Tertiary care hospital, Germany	NR	1049	Retrospective cohort study	Not living with a significant other, drug user, history of suicide attempt, daily use of barbiturates and cannabis	III-2	4
Olivier et al., 200937	University Hospital Toulouse, France	4 nonconsecutive weeks	789	Prospective cohort study	Number of medications taken, self-medication, use of antithrombotic and antibacterial drugs	II	4
Capuano et al., 200938	10 general hospitals in Regione Campania, Italy	10 days/ED in two study period	7861	Prospective cohort and nested case control study	Female gender and age category (30–39 and 60–69), patients taking RAS, NSAIDS, antibiotics, β-adrenoceptors agonist and β-lactam antibiotics	II	5
Zed et al., 200812	General hospital, Vancouver Canada	12 weeks	1017	Prospective observational study	Comorbidities, number of medications and multiple prescribers	II	5
Sauer et al., 200739	Administrative data, Florida, US	24 months	37,063	Retrospective cohort study	Age, male sex, number of medical conditions, and number of medications	III-2	2
Baena et al., 200640	University hospital, Granada, Spain	12 months	2261	Two-stage probabilistic sampling	Age, number of medications, and combined effect of the two	III-3	4
Tipping et al., 200641	Tertiary hospital, Cape Town, South Africa	4 months	517	Cross-sectional	Number of medications, patients taking NSAIDS, ACE- inhibitor, and warfarin	IV	3
Budnitz et al., 200676	9 NEISS, US	77 days	598	Retrospective cohort study	Use of warfarin and insulin	II-2	5
Trifiro et al., 200545	22 hospitals, Italy	10 days at intervals of 3 months	629	Prospective cohort study	Older age, male gender	II	4
Caterino et al., 200477	EDs of uninstitutionalised general hospital, US	NR	16.1 million	Retrospective cohort study	Number of medications at ED	III-2	4
Franceschi, et al., 200478	University hospital, Italy	10 days	607	Cross-sectional	Age and number of medications consumed	IV	3
Hafner et al., 200242	Teaching hospital, US	3 months	13,004	Case control	Old age, female gender, and polypharmacy	III-3	3
Malhotra et al., 20119	Referral hospital, India	7 months	578	Cross-sectional	Diabetes, patient living alone, poor recall of medication regimen, seeing multiple physicians, female gender, polypharmacy	IV	3

ADE: adverse drug event; ED: emergency department; NHAMCS: National Hospital Ambulatory Medical Care Survey; NESARC: National Epidemiology Survey on Alcohol and Related Conditions; NEISS-CADES: National Electronic Injury Surveillance System–Cooperative Adverse Drug Event Surveillance project; CVS: cardiovascular system; AHCA: Agency for Health Care Administration; RAS: renin-angiotensin system; NSAIDS: nonsteroidal anti-inflammatory drugs; ACE: angiotensin-converting-enzyme; NEISS: National Electronic Injury Surveillance System; US United States; NR: not reported.

^aNational Health and Medical Research Council level of evidence.

^bMixed Methods Appraisal Tool score.