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Evaluation of Text Message Reminders to Encourage Retesting for Chlamydia and Gonorrhea Among Female Patients at the Municipal Sexually Transmitted Disease Clinic in Seattle, Washington

Unutzer, Anna MPH; Dombrowski, Julia C. MD, MPH∗,†,‡; Katz, David A. PhD, MPH§; Barbee, Lindley A. MD, MPH†,‡; Golden, Matthew R. MD, MPH∗,†,‡; Khosropour, Christine M. PhD, MPH

Author Information
Sexually Transmitted Diseases: July 2020 - Volume 47 - Issue 7 - p 458-463
doi: 10.1097/OLQ.0000000000001184
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Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (GC) are the most commonly reported bacterial sexually transmitted infections (STI) in the United States (US) and can lead to adverse reproductive health outcomes for women.1,2 Women diagnosed with CT or GC are at high risk for reinfection, with an estimated 14.7% and 11.7% of women, respectively, reinfected within 6 months of an initial infection.3 Given the high probability of reinfection and data suggesting that the risk of adverse reproductive health outcomes increases with repeat infection,4 the Centers for Disease Control and Prevention recommends that individuals are retested for CT and GC 3 to 4 months after an initial positive test.2 However, retesting rates among women are suboptimal, with only 36% to 45% of women retesting within 6 months of an initial infection.5,6

Because undetected and untreated infections increase the risk of future reproductive tract disease and the risk of transmission to sex partners, several sexual health clinics have implemented reminder systems to alert patients when it is time to retest.7 Text message or short message system (SMS) reminders have been 1 intervention explored to encourage retesting, but data to support the effectiveness of this intervention are mixed, with several studies demonstrating success in increasing retesting rates among participants who received an SMS reminder,8–14 whereas other studies have seen little to no effect of SMS reminders on screening rates.15 Importantly, some of the most successful SMS reminder interventions required substantial resources to implement or were implemented in well-controlled research settings.10,11,16 Thus, it remains unclear if these types of reminders integrated into routine clinical practice will promote retesting for CT and GC among women within the recommended time frame.

In 2013, the Public Health-Seattle & King County (PHSKC) human immunodeficiency virus (HIV)/sexually transmitted disease (STD) Program began offering SMS reminders for retesting as part of partner services for men who have sex with men (MSM).17 The following year, the PHSKC STD Clinic initiated an opt-in, automated SMS reminder system integrated into the clinic's routine computerized clinical intake form to encourage HIV/STI retesting among MSM. In 2016, the clinic expanded the SMS reminder system to include female patients, with a focus of encouraging women diagnosed with CT or GC to retest. The objectives of this study were to examine the acceptance of these opt in reminders among women and to evaluate the effectiveness of SMS reminders among female patients to promote retesting for CT and/or GC and to identify subsequent reinfections.

METHODS

Study Design, Setting, and Population

We conducted a retrospective cohort study of data from the PHSKC STD clinic, a health department walk-in clinic. Our study population included cisgender female STD clinic patients who attended the clinic for a new problem visit between May 16, 2016 (the start of the SMS reminder program) and December 31, 2017, and who completed a computerized clinical intake form (described below).

During the study period, our clinic recommended that all women who tested positive for GC/CT were retested within 4 months, per national guidelines. The GC/CT test results were available to patients through the patient portal of the clinic's electronic medical record. Women who tested positive for GC/CT who had not been empirically treated at their initial visit were called by the clinic staff and informed of their test result. These women could return to the clinic for treatment or could request that a prescription be sent to the pharmacy of their choice.

Primary Exposure and Outcome

The primary exposure in this study was opting in to receive SMS reminders for retesting. The 2 primary outcomes were: (1) returning to the PHSKC STD Clinic for retesting within 3 to 6 months (91–182 days) of an initial positive CT or GC test; and (2) retesting positive for CT or GC within 3 to 6 months of an initial test. To allow for 6 months of follow-up time to accrue after an initial test, we included outcome data for patients through June 30, 2018. We chose a follow-up window of 3 to 6 months with the rationale that repeat testing in that interval could be attributable to the SMS reminder sent at 3 months after an initial positive CT or GC test result.

Data Sources and Measures

At the PHSKC STD Clinic, patients presenting for a new problem visit are asked to complete an electronic clinical intake form before seeing a clinician. The intake queries patients on demographics, sexual behavior history, STI and HIV history, and risk factors for HIV/STI; these data are stored in the STD clinic's electronic database. The SMS questions are integrated into this routine clinical intake. Based on responses provided within the intake, patients are asked either “question A” or “question B.” “Question A” stated: We recommend that you get tested for STDs (and HIV) every 3 months.Do you want us to send you a text message reminder or would you rather remember on your own? Women were asked question A if they (1) self-reported being previously diagnosed with HIV and either reported having a detectable viral load or reported not taking HIV medicine or receiving care in the past 6 months; or (2) self-reported having never tested positive for HIV and reported any of the following in the past 12 months: methamphetamine or poppers use, diagnosis of GC, CT, or syphilis. Women who did not meet these criteria were presented with “question B": If one of your tests today show that you have an STD, we recommend that you get STD testing in 3 months.Do you want us to send you a text message reminder or would you rather remember on your own? Women who responded to either question that they would like to receive a SMS reminder were asked to provide a phone number to receive the reminder; these women are consider to have “opted in” to SMS reminders. Patient responses to these questions and their phone numbers are stored in the STD clinic's electronic database. The phone numbers are not verified at the time the patient provides their number. Invalid phone numbers are identified by an error report generated once SMS messages have been sent. Patients were asked the SMS questions each time they presented to the clinic for a new problem visit, regardless of their previous responses to these questions.

For our first outcome (to identify women who returned to the clinic for retesting), we used the STD clinic's electronic database to identify women who tested positive for CT or GC on the date that they completed the clinical intake and answered the SMS reminder questions. Women are screened for CT or GC per national guidelines2 using nucleic acid amplification testing. During the study period, we used the APTIMA Combo-2 assay (Hologic, Inc, San Diego, CA).

For our second outcome (to identify women who retested positive for GC or CT within 3–6 months of an initial positive test), we used the Washington State Department of Health's electronic STD surveillance database (PHIMS-STD) for King County, which includes data from laboratories and medical providers. In WA state, all health care providers and laboratories are required to report cases of CT and GC to local health authorities, who subsequently provide data to WA Department of Health via PHIMS-STD. We used a deterministic match based on name and date of birth to match patient records from the PHSKC STD clinic to the STD surveillance database. Using surveillance data for all of King County allowed us to see if a woman tested positive for GC or CT after receiving the SMS reminder at a location in King County other than the PHSKC STD Clinic.

Statistical Analyses

We used χ2 tests for categorical variables and t tests for continuous variables to compare characteristics of women who did and did not opt in to SMS reminders. We compared these characteristics among our overall study population and separately for those who tested positive for GC or CT at their initial visit.

We assessed the number and percentage of women who returned to the clinic within 3 to 6 months after an initial positive test among those who did versus did not opt in to receive reminders and present exact binomial confidence intervals (CI) for these percentages. We used Fisher exact test to test for statistically significant differences in these numbers. We also used Fisher exact test to compare the proportion of women who retested positive for CT or GC within 3 to 6 months of an initial positive test, comparing those who did with those who did not opt-in to receive SMS reminders.

All analyses were conducted using Stata/IC 15.1 (StataCorp, College Station, TX). Tests were performed at a significance level of 0.05. Study procedures and analyses were approved by the University of Washington Human Subjects Division.

RESULTS

Of the 2250 women who completed the computerized clinical intake form between May 2016 and December 2017, 2067 (92%) women were presented with the SMS opt in questions (Fig. 1). Overall, 743 (36%) of 2067 women opted to receive the SMS reminder and 1324 (64%) women did not opt in to receive the reminder. Compared with women who did not opt in to SMS reminders, women who opted in were significantly more likely to report 3 or more sex partners in the past 2 and 12 months but less likely to report a history of CT or GC in the past year (Table 1). There were no other statistically significant differences between the 2 groups.

Figure 1
Figure 1:
Flow chart of SMS reminder opt-in and GC/CT test positivity among women completing a computerized intake at the PHSKC STD Clinic (N = 2250). *This percentage is not 100% because the SMS questions are at the end of the clinical intake and not all patients complete the intake in its entirety.
TABLE 1
TABLE 1:
Characteristics of Women Who Did and Did Not Opt in to a 3-Month Text Message Reminder for Retesting, by Opt in Status (N = 2067)

Of the 2067 women asked about SMS reminders, 112 (5.4%) tested positive for CT (n = 67), GC (n = 41), or both CT and GC (n = 4). Seventeen (15%) of these women provided invalid phone numbers and were excluded from further analyses. The 95 women who tested GC- or CT-positive at their initial clinic visit and provided a valid phone number were younger than the overall study population (mean age, 28 years). Less than 30% were non-Hispanic white, and one third reported contact to a partner with GC or CT. Of these 95 women, 33% (n = 31) opted in to receive reminders, and 67% (n = 64) did not opt in to reminders. Differences between women who did and did not opt in to reminders were similar to those noted for the overall study population (Table 2).

TABLE 2
TABLE 2:
Characteristics of Women Who Did and Did Not Opt in to a 3-Month Text Message Reminder for Retesting, Among Women Who Tested STD Positive* at Initial Visit, by Opt-in Status (N = 95)

Over half of the 95 women who tested positive for CT or GC at their initial visit did not return to the clinic at any point during the study period, and only 14% returned to the clinic within 3 to 6 months (Table 3). Among women who opted in to receive SMS reminders (n = 31), 23% (95% CI, 10–41%) returned to the clinic for retesting within 3 to 6 months compared with 9% (95% CI, 4–19%) among those who did not opt in to receive reminders; this difference was not statistically significantly different (P = 0.11).

TABLE 3
TABLE 3:
Number and Percent of Women Who Returned to the STD Clinic for Retesting Among Those Who Tested Positive for GC or CT at Their Initial Visit, by SMS Opt in Status (N = 95)

Ten (10.5%) of 95 women retested positive for CT or GC during the study period, but only 4 women retested positive within 3 to 6 months of an initial positive test (Table 4). The percent of women who retested positive within 3 to 6 months was not significantly different for women who had opted in to receive reminders (2 [6%] of 31) compared with those who did not opt in to receive reminders (2 [3%] of 64) (P = 0.59).

TABLE 4
TABLE 4:
Number and Percent of Women Who Retested Positive for GC or CT* Among Those Who Tested Positive for GC or CT at Their Initial Visit, by SMS Opt in Status (N = 95)

DISCUSSION

In this evaluation of an SMS reminder system to increase retesting for CT and GC among female STD clinic patients, we found that only about one third of the women opted in to receive SMS reminders for STD retesting. Women who did and did not opt in were generally similar in terms of demographics, although women who opted in reported more sex partners than those who did not opt in. Among all women who initially tested positive for CT or GC, only 14% returned to the clinic for retesting within 3 to 6 months. Although a higher percentage of those who received an SMS reminder returned to the clinic for retesting within 3 to 6 months compared with those who did not opt in (23% vs 9%), this difference was not statistically significant. Very few women (4%) retested positive for CT or GC 3 to 6 months after an initial infection, and we did not observe a significant difference in retest positivity among women who did and did not opt in (7% vs 3%). Our findings suggest that SMS reminders for retesting are not widely embraced by this patient population but may have had a modest influence on women returning to the clinic for retesting. This study highlights the need for more robust interventions to improve retesting for GC and CT among women.

One of our study's main objectives was to assess the acceptance of SMS reminders among female STD clinic patients. We found that 743 (36%) of 2067 women opted to receive the SMS reminder, a number that is comparable to other studies of SMS reminders that have observed overall acceptance rates for SMS reminders of 31% to 68%.10,12,18,19 Interestingly, the acceptance of SMS reminders in our study (acceptance, 36%)—where we asked patients about opting in to SMS reminders before being tested for GC or CT—is nearly identical to that noted in a Dutch study by Kampman and colleagues10 among STD clinic patients who were asked to enroll in SMS reminders after receiving a positive CT test (acceptance, 39%). These studies highlight that, in general, SMS reminders for retesting are not overwhelmingly popular and may not necessarily be influenced by whether or not someone has tested positive for an STI.

Among the women in our study who initially tested positive for CT or GC, the proportion who opted in to receive an SMS reminder and who returned to the clinic for retesting (23%) is slightly lower than previous studies, which have found that between 26% and 61% of women who received an SMS reminder returned to the clinic to retest.8–11,15,16 However, the proportionate difference (ie, absolute difference in percentages) in retesting rates between women who did and did not opt in to receive reminders in our study (17%) is similar to other studies which have noted differences of 9% to 33%.8–11,15,16 Although the difference in retesting rates that we observed was not statistically significant, its consistency with other studies—which include those in research environments and public health clinics, those in Europe and Australia, and those that used a variety of study designs and different retesting windows—highlights that these reminders may have an impact, albeit modest, on encouraging some individuals to return for retesting.

Given other studies' estimates that 12% to 15% of women retest positive for GC/CT within 6 months of an initiation diagnosis,3 we were somewhat surprised that, among women in this study initially diagnosed with GC or CT, only 7% were GC- or CT-positive again within 6 months of treatment for the initial infection. This proportion was also well below that noted in the aforementioned study by Kampman and colleagues,10 where the proportion of patients who received an SMS reminder and retested positive for CT was 20%, although that study included outcomes beyond 12 months. However, similar to the Kampman study, we did not observe a significant difference in retest positivity among women who did and did not opt in to receive SMS reminders. Of note, a large and methodologically rigorous study of MSM STD clinic patients in Australia12 found that receipt of SMS was associated with higher detection rates for rectal GC and CT and urethral CT. Thus, it is unclear if the apparent lack of an effect of SMS reminders on retest positivity among women is due to differences in study populations (ie, MSM vs women) or methodologic considerations (eg, prospective vs retrospective design).

Given our study's observations of a relatively low uptake of SMS reminders for retesting, of a relatively modest effect of SMS reminders to encourage retesting, and of little or no effect of SMS reminders to identify repeat CT/GC infections, it is unclear if these reminders should continue to be implemented for women. To the extent that these reminders may promote retesting among a small group of women, it may be worthwhile and important to continue providing this service to patients in settings where SMS reminders are integrated into a clinic's existing infrastructure and can operate with few resources. However, clinics that would need to invest substantial resources to develop and maintain an SMS reminder system may wish to seek out additional evidence on the effectiveness and cost-effectiveness of these reminders before considering their implementation. In fact, our clinic no longer offers SMS reminders to patients as of December 2018, when we transitioned to new software for our clinical intake that did not readily allow integration of SMS reminders. In light of the results of this study, we determined that the resources required to integrate SMS reminders into the new system was greater than the anticipated benefit to our patients. It may be worthwhile for clinics to look further into the possibility of different digital interventions to promote retesting or screening, or interventions that also include distribution of home specimen collection kits, because these could have a greater impact than the use of SMS alone.16,20

This study has several strengths. First, we evaluated an existing SMS reminder system that was integrated into clinical practice, which allowed us to examine the impact of the SMS intervention in a “real-world” setting. Second, we utilized King County surveillance data to capture outcomes among women who retested CT- or GC-positive at any location in King County. This study also has several limitations. First, this was not a randomized trial, and women who chose to opt in to the SMS reminder for retesting may have been more likely to retest for CT or GC even in the absence of receiving a reminder. Second, we did not capture information on women who retested negative for CT or GC in another clinic outside of the PHSKC STD clinic, thus the retesting rates we present are likely a minimum proportion of the women who retested. We also did not capture positive tests that occurred outside of King County. Third, the PHSKC STD clinic has a large MSM patient population, and the number of women seen at the clinic annually is small, resulting in a small sample size for this study. This small sample size limited our ability to adjust for differences in characteristics between women who did and did not opt in to the SMS reminders. This has important implications because, as noted above, women who opted in to receive reminders may have been more likely to retest. Fourth, we did not ask patients why they did not choose to opt into SMS reminders. This information would have been informative to be able to enhance our clinic's efforts to improve retesting rates. Finally, we used a deterministic algorithm to match STD clinic data with King County surveillance data, and it is possible that our match did not identify some women who truly retested positive.

In conclusion, we found that retesting rates for CT and GC among women remained suboptimal even among women who received SMS reminders for retesting. The SMS reminders may encourage some patients to retest, but they do not appear to be unanimously accepted nor are they a “silver bullet” to promoting retesting for CT and GC among women. Given that STI rates are at an all-time high and that retesting rates in the US are unacceptably low and do not appear to be improving, our findings highlight the need to develop and implement innovative, low-cost, and patient-accepted methods to encourage STI retesting and to conduct methodologically rigorous studies to evaluate their effectiveness.

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