Do patients use online messaging to substitute for office visits and phone calls? Results from a natural experiment
We evaluated the effect of online messaging between patients and providers on other healthcare utilization. Messaging may increase the administrative burden on providers but may also substitute for utilization such as calls or visits. Previous studies were either conducted early in the implementation of secure messaging with small numbers of patients or they focused on the usage of the entire online patient portal. To identify the effect of messaging, we exploited a natural experiment, which occurred in 3/2011, when a large multispecialty practice in California lowered the price of messaging from $60/year to free for patients and initiated incentives for doctors ($3/thread), resulting in increased rates of patients messaging.
Methods
We conducted a longitudinal study of 65,332 active primary care patients from 3/2009-3/2012. All patients in the study had activated their online portal before 3/2011 and none had paid to use messaging previously; 38,438 of these patients initiated a message following 3/2011. Messaging was measured by the number of threads initiated by patients annually. Propensity scores of the likelihood to message were estimated based on patient demographics, Charlson score, utilization, continuity of care and provider characteristics. One-to-one matching resulted in a sample of 51,198. Outcome measures included annual rates of office visits and phone calls to primary and specialty care. The effects of messaging were identified through difference-in-differences analyses using generalized least squares, comparing the utilization of those initiating any messages with those not messaging, before and after messaging became free. Controls included patient fixed effects along with patient age, insurance type, Charlson score, continuity of care, and relevant characteristics of their primary care provider.
Results
Before 3/2011, when no patients messaged, the average number of annual office visits was 2.22 for primary care and 3.66 for specialty care; the annual number of phone calls was 2.24 for primary care and 1.92 for specialty care. After 3/2011, the secure messaging users initiated an average of 1.27 threads per year. Comparing the rates of service use before and after 3/2011, between messaging and non- messaging users, we found a negligible difference in the annual number of primary care phone calls (0.030 per patient-year, P<0.001) and a small increase in primary care office visits (0.064 per patient-year, P<0.001) for each thread initiated. For specialty care, we found an increase in 0.181 phone calls (P<0.001) and 0.248 (P<0.001) office visits per patient-year for each thread initiated.
Conclusions
Comparing a propensity score matched sample of patients using an online portal that did and did not send secure messages, we found that use of secure messaging was associated with little difference in primary care utilization, but with a moderate increase in specialty utilization. These findings raise questions about whether cost savings may be achieved through secure messaging offsetting more traditional utilization.