Table 3.

Characteristics of the included studies.

Study number	Reference	Country	Sample size	Period	Main outcomes
1	Adler-Milstein et al [24]	United States	191 hospitals	2 years	EHRa adoption is associated with better performance in terms of payment and length of stay in well-run institutions. EHR adoption may be associated with worse performance in poorly run institutions.
2	Adler-Milstein et al [25]	United States	2591 hospitals (2011)	4 years	Degree of EHR adoption is positively correlated with process adherence, patient satisfaction, and efficiency.
3	Castellanos et al [26]	Germany	Not indicated	6 years	Small increase in profit in the year after the introduction of the patient data management system.
4	DesRoches et al [27]	United States	3049 hospitals	6 months	Presence of clinical decision support is associated with small quality gains. No relationship between EHR level and overall risk-adjusted length of stay, risk-adjusted 30-day readmission rates, and risk-adjusted inpatient costs.
5	Elnahal et al [28]	United States	3101 hospitals	9 months	Higher rates of adoption of key EHR functions among high-quality hospitals.
6	Encinosa and Bae [29]	United States	2619 hospitals	1 year	EMRsb do not reduce the rate of patient safety events. In case of patient safety events, EMRs reduce deaths, readmissions, and spending.
7	Feblowitz et al [30]	United States	Not indicated	2 years	Length of stay increased after implementation of an electronic documentation. Mean time to disposition for admitted patients remained stable.
8	Furukawa et al [31]	United States	5066 hospitals	10 years	Advanced EMR applications may increase hospital costs and nurse staffing levels, as well as increase complications and decrease mortality for some conditions.
9	Furukawa et al [32]	United States	509 hospitals	5 years	Nurse-sensitive patient outcomes improved. EMR implementation may be associated with reduced demand for nurses.
10	Himmelstein et al [33]	United States	4000 hospitals	6 years	Hospital computerization has not achieved savings on clinical or administrative costs. More computerized hospitals might have a slight quality advantage for some conditions.
11	Jarvis et al [34]	United States	2988 hospitals	1 year	Most advanced EHRs have the greatest payoff in improving clinical process of care scores.
12	Jones et al [35]	United States	6057 hospitals	4 years	Availability of basic EHR is associated with a significant increase in health care quality for heart failure.
13	Joynt et al [36]	United States	1236 hospitals	4 years	Patients with stroke are more likely to receive guideline-driven components of care at hospitals with EHRs. Patients are slightly less likely to have a hospital stay longer than 4 days at hospitals with EHRs.
14	Kazley et al [37]	United States	1000 hospitals	1 year	In hospitals with advanced EHRs, patient costs are less compared with hospitals without advanced EHRs.
15	Lee et al [38]	United States	708 hospitals	8 years	Hospitals adopting EMRs experience shorter length of stay and lower 30-day mortality.
16	McCullough et al [39]	United States	3401 hospitals	4 years	Use of EHRs results in improvements in process-of-care measures for patients with heart failure or pneumonia.
17	Nakagawa et al [40]	Japan	Not indicated	7 years	EMR may decrease medical risks, but profitability does not rise more than the investments.
18	Schenarts et al [41]	United States	Not indicated	40 months	Implementation of the EMR is associated with an improvement in several complications and process measures.
19	Teufel et al [42]	United States	2307 hospitals	1 year	Advanced-stage EMR is associated with greater costs per case.
20	van Poelgeest et al [43]	Netherlands	67 hospitals	1 year	No statistically significant association between a hospital’s EMR adoption and an overall quality or safety performance.
21	Xue et al [44]	China	251 physicians and 298,760 patient visits	5 years	Length of stay declines and mortality rate decreases with EMR. An EMR has no positive effect on patient costs.
22	Yanamadala et al [45]	United States	448,767 patients	1 year	Patients at hospitals with full EHR have the lowest rates of inpatient mortality, readmissions, and patient safety indicators.
23	Zlabek et al [46]	United States	Not indicated	Not indicated	Implementation of an inpatient EHR results in a rapid improvement in measures of cost of care.

^aEHR: electronic health record.

^bEMR: electronic medical record.