Yi Yvonne Zhou, PhD; Terhilda Garrido, MPH; Homer L. Chin, MD; Andrew M. Wiesenthal, MD; and Louise L. Liang, MD
Widespread efforts to improve healthcare quality, safety, and efficiency focus on using information technologies such as electronic health records, patient registries, computerized physician order entry, embedded decision supports, and others. Among these, electronic patient–physician messaging has been viewed as a promising technology to improve the quality and efficiency of healthcare.1
Electronic communication between patients and physicians can reduce health plan spending on physician office and laboratory services.2
Patients and physicians alike indicate satisfaction with electronic messaging.3,4
Ninety percent of US consumers with Internet access indicate a clear preference for online communications with healthcare providers.5
Complex issues of reimbursement, confidentiality, and liability have impeded widespread adoption of patient–physician electronic messaging in the United States. However, these issues appear to be resolving. Following the American Medical Association's 2004 approval of online consultation billing, some US insurers have recently offered reimbursement for its use.5,6
Similarly, secure Web messaging represents a security improvement over e-mail, reduces liability,7,8
and is increasingly available as a stand-alone service to physicians without electronic health record systems.9
Some physicians may be concerned that the use of secure messaging would increase their overall workload. 10
The extent to which secure messaging can substitute for office visits or telephone contacts is unclear. Previous studies offer conflicting evidence: telephone communication is not impacted by electronic messaging,11,12
office visits are reduced,13,14
and both telephone contacts and office visits are reduced by electronic communication.15
These studies were small in size and limited in scope; the largest involved roughly 1000 health-related messages.12
To investigate the relationship between patient–physician electronic messaging and physician workload, we evaluated the impact of patient access to an electronic health record with secure patient–physician messaging on primary care office visit and documented telephone contact rates in an entire Kaiser Permanente (KP) operating region.
KP is the nation's largest not-for-profit integrated healthcare delivery system with more than 8.5 million members in 8 geographic regions. Professional partnerships in each region employ physicians and contract with the not-for-profit Kaiser Foundation Health Plan to arrange necessary medical care for members.
KP's integrated healthcare delivery system addresses all healthcare needs for adult and pediatric members, including preventive, routine, specialty, emergency, and inpatient care; ancillary testing; pharmacy and rehabilitative services; and home care. The Kaiser Permanente Northwest (KPNW) region, with nearly 487 000 adult and pediatric members in April 2006, is located in Oregon and southwest Washington. KP HealthConnect™ Online
KP is implementing an integrated electronic health record throughout the entire enterprise.16
Based on software supplied by Epic Systems, it is known as KP HealthConnect™. Members can access parts of their individual health records through a secure member Web site: www.kp.org. After registering as users, they may take advantage of all KP HealthConnect™ Online features (Table 1
). Messaging takes place within a secure Web environment. User accounts are activated by passwords mailed to members' homes, and all messaging takes place in an authenticated/encrypted environment and behind an enterprise-level firewall.
Members are clearly informed that receiving a response to a secure message may take up to 2 business days and that messaging is only appropriate for nonurgent concerns. The member-only Web site, www.kp.org, contains the following warnings on the secure messaging screen: "Do not attempt to access emergency care through this Web site … call 911 or go to the nearest hospital." "If you have an urgent symptom or want to speak with a nurse, do not use this Web site. Please call your local Kaiser Permanente facility."
KP HealthConnect™ Online was first implemented as a pilot project (Personal Health Link) in November 2002 for adult members in the Northwest region. As of September 2005, 18 094 members were registered users, representing 6% of the total KPNW adult membership. Design
To evaluate the impact of KP HealthConnect™ Online on primary care office visit and documented telephone contact rates, we conducted a pair of retrospective studies. The 2 designs relied on administrative data about subject characteristics, primary care office visit and telephone contact rates, and KP HealthConnect™ Online use. The use of complementary designs allowed us to examine the impact of secure messaging in 2 ways: in the largest possible sample and while controlling for factors that might impact validity. Cohort Study.
A retrospective cohort study included 4686 adult members who were registered KP HealthConnect™ Online users for longer than 13 months, had used at least 1 feature, and were continuously enrolled as KPNW members during the study period. Cohort subjects must have registered to use KP HealthConnect™ Online by August 2004. For the majority, the study period occurred between September 2002 and August 2005. Cohort subjects were on the patient panels of approximately 250 primary care physicians. Matched-control Study.
A retrospective matched-control study included 3201 subjects who were also part of the cohort described above. For each, we identified and randomly selected control matched by age, sex, selected chronic conditions (eg, diabetes, congestive heart failure), and primary care physician.
For both studies, we defined the pre-period as 3 to 14 months before KP HealthConnect™ Online registration and the post-period as 2 to 13 months afterward. Immediately around the time of registration, outpatient visit rates for subjects in both the cohort and matched-control studies were above baseline levels because many people learned about KP HealthConnect™ Online during clinic visits for active health concerns. To conservatively estimate the impact on utilization of access to KP HealthConnect™ Online, we omitted this spike in outpatient visit and telephone contact rates from our analysis.
Outcome variables included annual adult primary care office visit rates, comprising appointments with physicians and physician extenders (nurse practitioners and physician assistants) in adult primary and urgent care (nonemergency) settings. Documented telephone contact rates included both scheduled telephone visits and unscheduled telephone calls to and from internal medicine and family practice physicians, nurse practitioners, and physician assistants. Statistical Analysis
We used the x2
test to look for differences in age/sex and the prevalence of diabetes and congestive heart failure between 5 groups of interest: the 323 296 adult members of KPNW, 18 094 KPNW members who had registered with KP HealthConnect™ as of September 2005, the 4686 cohort subjects, the 3201 subjects of the matched-control study, and the 3201 controls of the matched-control study. Differences in office visit and telephone call rates were symmetric about the mean, although not normally distributed based on the formal normality test. However, because percent changes in mean utilization rates are the most operationally meaningful way of examining trends, and parametric tests are robust to deviations from Gaussian distributions when samples are large,17
we used the paired t
test to assess the statistical significance of differences in utilization rates over time and across groups. As a matter of interest, the Wilcoxon rank sum test and the paired t
test yielded identical statistical significance.Cohort Study.
We calculated the difference in primary care office visit and documented telephone contact rates between the pre- and post-periods, assessing statistical significance with the paired t
We calculated the difference in primary care office visit and documented telephone contact rates in the pre- and post-periods for subjects and for controls, again assessing statistical significance with the paired t
test. In addition, we also used the paired t
test to assess the statistical significance of the variation in rate changes between the subject and control groups.
In general, KP HealthConnect™ Online users were older and included a higher proportion of members with diabetes than did the general adult membership. Similarly, cohort members were older and included a higher proportion of individuals with diabetes than did the larger user population. The differences in age/sex and the proportion of members with diabetes between the cohort and the general adult membership were significant (P
< .0001). By design, cohort subjects and both groups in the matched-control study did not differ to a statistically significant degree in terms of age and the proportion of members with diabetes. Table 2
summarizes these results. Annual Adult Primary Care Office Visit Rates
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