Text message reminders for parents to get their children a flu shot boosts immunization rates but not by much, a clinical trial determined.
In a low-income, urban population, a series of text reminders yielded a vaccination rate of 43.6% compared with 39.9% in families given just the usual single phone reminder, Melissa S. Stockwell, MD, MPH, of Columbia University School of Public Health in New York City, and colleagues found.
While statistically significant at a P-value of 0.001, the difference by the end of influenza season was small at a relative 9% and an absolute 3.7%, they reported in the April 25 issue of the Journal of the American Medical Association.
Although modest, it's a step forward that's likely to become a routine part of the complex system of preventive healthcare delivery, Peter G. Szilagyi, MD, MPH, of the University of Rochester, in Rochester, N.Y., and William G. Adams, MD, of Boston University, noted in an accompanying editorial.
"At a population level, an increase of even four percentage points is important," they wrote. "If applied across the U.S., it could represent an additional 2.5 million children and adolescents who receive influenza vaccination."
Postcards or telephone calls to the family to remind them of the need to come in for vaccination are recommended but not often used because of the logistic challenge, the editorialists pointed out.
One advantage of text messages is that cell phone numbers tend to be more stable than home address or home phone numbers. Also, texting reaches the intended recipient directly with information visibly accessible for future use.
"The potential is substantial, and in the right setting with automated, integrated information systems, text message reminders can target large numbers of patients at relatively low cost," Szilagyi and Adams explained.
The study leveraged an electronic medical record system and a city-wide immunization registry, which made the intervention feasible.
The researchers enrolled 9,213 children 6 months to 18 years of age at four community-based pediatric clinics serving a primarily Latino, publicly-insured population almost universally eligible for free vaccines and randomized them to one of two reminder strategies during the 2010-2011 influenza season.
The usual care group got an automated telephone reminder about the seriousness of influenza infection, availability of a safe vaccine, and clinics open on Saturdays for immunization.
The intervention group got the same voice message along with a series of five weekly text messages conveying similar information.
Messaging costs for the entire study ran only $165 for the more than 23,000 texts sent, although modifying the reminder system and programming it cost upwards of $7,000.
Besides looking at the primary endpoint of vaccination by the end of the flu season in March, a second analysis showed a modest boost in the percentage of children who got vaccinated early in November or December as recommended (27.1% versus 22.8%, relative rate ratio 1.19, P<0.001).
A sensitivity analysis showed a bigger impact of the program when looking only at those with messages that could be delivered, "lending support to the inference that text messaging was effective in promoting the behavioral changes leading to increased vaccination."
The immunization rates were 46.3% with text message reminders versus 39.9% with the usual phone call overall by the end of the flu season and 29.3% versus 22.8% early in the flu season (both P<0.001).
The researchers cautioned that the low-income, urban population served likely faced many other competing priorities and barriers not addressed by the texting intervention that kept the vaccination rates low.
Further studies are needed to determine the optimal way to use texting as a medium for public health messages, they noted.
The editorialists agreed, noting, for example, that the messages sent as part of the study weren't actionable.
"Future studies might examine the incremental benefit of including a telephone number that could be called immediately to schedule an appointment or perhaps one that could scan an online calendar to propose a few available times for vaccination," they suggested.
Generalizability to populations other than low-income families in urban areas wasn't clear.
The study was supported by grant funds from the Maternal and Child Health Bureau.
The researchers and editorialists reported having no conflicts of interest to disclose.
- Reviewed by Dori F. Zaleznik, MD Associate Clinical Professor of Medicine, Harvard Medical School, Boston and Dorothy Caputo, MA, BSN, RN, Nurse Planner
Journal of the American Medical AssociationSource Reference: Stockwell MS, et al "Effect of a text messaging intervention on influenza vaccination in an urban, low-incomepediatric and adolescent population: A randomized controlled trial" JAMA 2012; 307: 1702-1708.
Journal of the American Medical AssociationSource Reference: Szilagyi PG, Adams WG "Text messaging: A new tool for improving preventive services" JAMA 2012; 307: 1748-1749.