Community Study to Reduce High Blood Pressure Through Text Messaging (REACH OUT): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Community Study to Reduce High Blood Pressure Through Text Messaging (REACH OUT) (NCT02664610), a randomized na study. The primary outcome is Mean Change in Systolic Blood Pressure.

2. Clinical Question

The trial’s stated rationale connects hypertension with stroke risk and describes hypertension as a modifiable risk factor. The study therefore tested a community-based approach using mobile-phone messages, with change in systolic blood pressure as its primary outcome. The secondary outcome was mean change in diastolic blood pressure.

The registry record identifies random assignment to the two groups, but does not report the allocation ratio, the detailed eligibility criteria, or a more specific definition of usual care or health information. It also does not report the primary outcome estimates, the uncertainty around a between-group comparison, or a statistical test result. Consequently, the research question can be described, but the size and precision of the observed difference cannot be assessed from the registry record.

3. Trial Design

This was a randomized, parallel-group behavioral study of text messaging for people with high blood pressure. The registry record lists an enrollment of 94. Participants were assigned either to receive text messages or to receive health information without text messages. The record describes the study as unmasked, meaning masking is recorded as none; it does not give further details about who knew each participant’s assignment.

The study is described as taking place in an urban African American community in Flint, Michigan, using a community-based participatory research approach. The registry record identifies University of Michigan as the sponsor. The recorded start was 2014-02, primary completion was 2015-04, and status is completed. Phase is recorded as NA.

The primary outcome was mean change in systolic blood pressure, in mmHg, from baseline to 6 months. Mean change in diastolic blood pressure is listed as a secondary outcome. Although the record lists two outcome measures and two analyses, it does not report the analysis methods, the analysis populations, or how participants with unavailable measurements were handled. The allocation ratio and details of the randomization procedure are not reported in the registry record.

The comparison is between assignment to a text-messaging intervention and assignment to health information without text messages. It is not a comparison of text messages with no health information: the control-group description says participants received health information. The registry record does not detail that information, the intervention’s message content or frequency, or whether other aspects of care were the same between groups. These missing details limit how specifically the intervention contrast can be characterized.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Mean Change in Systolic Blood Pressure, measured over Baseline to 6 months.

The primary endpoint is mean change in systolic blood pressure from baseline to 6 months, measured in mmHg. It is a continuous outcome: each participant’s change is a numerical measurement, and a group mean describes the average change among participants with measurements included in the analysis. The registry record names the endpoint but does not report the arm-level means, the spread of individual changes, or a between-group estimate.

As a general statistical explanation, measuring change compares a follow-up measurement with a baseline measurement for the same participant. Comparing the average changes between randomized groups can describe whether their observed trajectories differed over the follow-up period. A mean alone does not show how varied individual measurements were, so a measure of dispersion, such as the standard deviation, is useful for describing the spread of observations. The registry record identifies standard deviation as the dispersion measure, but numerical values are not reported in the registry record.

The endpoint is used because blood pressure is the direct measurement targeted by the intervention. The registry rationale links hypertension with stroke risk and calls hypertension a modifiable stroke risk factor. A change in a blood-pressure measure therefore addresses the stated study objective; it is not itself a count of strokes or proof of a change in stroke outcomes. The timeframe is baseline to 6 months, and the registry record does not report additional primary-outcome time points in a form that permits a single comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a continuous primary outcome: mean change in systolic blood pressure from baseline to 6 months. It names the standard deviation as the measure of dispersion. It does not report a statistical analysis plan or the numerical outcome results. Accordingly, the explanations below describe general statistical concepts rather than methods confirmed as having been used in this trial.

What does a mean change describe?

As a general statistical principle, a change score represents a participant’s follow-up measurement relative to that participant’s baseline measurement. Averaging these changes within a group gives the group’s mean change. A comparison of group mean changes summarizes the average difference in trajectories over the specified timeframe. The mean does not describe every participant’s experience, and it can be affected by unusually high or low values. The registry record does not report how individual measurements were summarized or whether the primary comparison used change scores or another model.

Standard deviation describes how spread out observations are around their mean. When individual outcomes vary substantially, the mean alone gives an incomplete picture of the data. The registry record names standard deviation as the dispersion measure but does not report its numerical value for either group. It also does not report whether the standard deviation refers to change scores or another quantity, so that detail is not reported in the registry record.

How should a group contrast be read?

As a general explanation, an estimated between-group contrast expresses the difference in average outcome between the assigned groups, using a defined sign convention. For a change outcome, the contrast may be expressed as the difference between mean changes. Its interpretation depends on knowing which group is subtracted from which, and whether the analysis adjusts for baseline measurements or other variables. The registry record does not report a numerical contrast or its sign convention.

A confidence interval gives a range of values compatible with the observed data and the model used to calculate it. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. The interval is not a guarantee that the true value lies within its bounds. Because no numerical interval is reported in the registry record, the precision of the primary or secondary outcome estimates cannot be assessed.

A p-value is calculated under a specified statistical model and null hypothesis. As a general principle, it measures how compatible the observed data are with that null model; it is not the probability that the null hypothesis is true and does not measure clinical importance. A p-value should be considered alongside the effect estimate and confidence interval. The registry record does not report a p-value for either outcome, and the analysis plan is not reported in the registry record.

Why does the analysis model matter?

As a general statistical explanation, the analysis model determines how the observed measurements are converted into estimates and uncertainty. A simple comparison of mean changes and a model that adjusts for baseline measurements may produce different estimates or standard errors. Repeated measurements, clustering, and departures from model assumptions can also affect analysis choices. The registry record does not report whether any of these features were addressed, so no particular model should be attributed to the trial.

Over-dispersion is a general issue for outcomes whose variability exceeds what a chosen model expects. If a model assumes less variability than the data contain, standard errors can be too small and confidence intervals too narrow. This concept is not a claim that over-dispersion occurred in this study: the record identifies a continuous mean outcome and standard deviation, and does not report a model assessment or evidence of over-dispersion.

What can a planning calculation tell a reader?

The registry description of the planning illustration specifies a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says the target effect is a stated fraction of the observed effect. These are planning assumptions, not outcome findings. Such calculations estimate the participants per arm needed under the chosen assumptions; they do not describe how many participants actually contributed to an endpoint analysis. Numerical planning values and the observed effect used for the illustration are not reported in the registry record. A planning illustration is not observed power, and it does not establish that the trial detected an effect.

The record does not report a sample-size justification for the original design, a prespecified target effect, or an analysis plan for the primary comparison. Therefore, the planning assumptions should not be mistaken for the trial’s original design rationale. No recalculated estimate from posted summary statistics is described in the registry record details.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists systolic blood-pressure change as the primary outcome and diastolic blood-pressure change as a secondary outcome. It also reports two outcome measures and two analyses. The primary outcome is described as having several categories or time points and not being reduced to one comparison. These features matter because testing multiple outcomes, time points, or comparisons can increase the chance of finding an apparently notable result by chance if results are interpreted without a prespecified strategy.

As a general statistical principle, a multiplicity plan specifies which comparisons are primary and whether or how inference is adjusted when several hypotheses are tested. The registry record identifies primary and secondary outcomes, but the approach to multiplicity, the selected comparison for the primary outcome, and any adjustment are not reported in the registry record. The numerical results for the listed outcomes are also not reported in the registry record, so the consequences of any testing strategy cannot be evaluated.

The registry record does not report the number of participants with available measurements for either outcome, reasons for missing measurements, or methods for handling missing data. It also does not report whether the analysis included all randomized participants, only participants with observed measurements, or another analysis population. Missingness should not be assumed to be absent merely because its amount is not reported. Without these details, it is not possible to assess whether the analyzed measurements represent the assigned groups or whether missing data could have affected estimates.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record lists zero serious adverse events in the no-text-message group, with 46 participants at risk, and zero in this discussion-message group, with 48 participants at risk. It also lists zero other adverse events in each group, using the same respective at-risk counts. These are the recorded counts for the groups; they should not be read as proof that no unrecorded events occurred.

Deaths are marked as null for both groups. Death counts are therefore not reported in the registry record, rather than being reported as zero. The registry record does not list serious adverse-event terms, and the top serious-event terms list is empty. It does not provide further detail about event definitions, collection procedures, duration of safety monitoring, or how the at-risk counts were determined. The counts describe the safety information recorded, not a complete assessment of all possible harms or a comparison that establishes safety.

12. What the Result Does, and Does Not, Mean

The registry record describes a randomized comparison of text messages with health information without text messages among participants with high blood pressure. It names mean change in systolic blood pressure from baseline to 6 months as the primary outcome and mean change in diastolic blood pressure as a secondary outcome. Those details define the study question, but they do not establish what the comparison found.

The numerical outcome estimates and their uncertainty are not reported in the registry record. It is therefore not possible to state whether the groups differed in average blood-pressure change, which group had a larger change, or how precise an estimated contrast was. Missing results are not evidence of no effect, and the study’s randomized design does not by itself supply the absent estimates.

As a general statistical distinction, a change in a measured outcome is not the same as a change in a later health event. The registry rationale connects hypertension with stroke risk, but the listed primary endpoint measures systolic blood pressure, not stroke incidence. The record lists stroke among the conditions and does not report a stroke outcome result. Thus, the endpoint alone cannot establish an effect on stroke.

The registry’s serious-event counts are limited to the recorded zero counts and listed at-risk groups; death information is not reported in the registry record. These entries do not replace complete safety reporting or establish the absence of risk. More broadly, the record does not report the analysis populations, missing-data handling, or detailed methods, all of which would inform interpretation of any numerical estimate. The most defensible reading is therefore descriptive: the study design and intended outcomes are recorded, while the primary and secondary outcome results needed to assess the treatment contrast are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically notable for asking a focused behavioral question in a community-based setting: whether a mobile-phone text-messaging intervention was associated with a different change in systolic blood pressure than health information without text messages. Random assignment and a parallel-group design define a comparative framework, while the baseline-to-6-month endpoint provides a stated period over which change was to be measured.

The record also illustrates why a registered endpoint and a registered design are not enough to interpret a result. Means, measures of dispersion, a between-group estimate, and its uncertainty are needed to assess direction, size, and precision. Those numerical outcome results are not reported in the registry record. Consequently, the study question can be understood, but the available information does not support a statistical conclusion about the primary comparison.

Its outcome structure also raises general interpretive issues: more than one blood-pressure measure is listed, and the primary endpoint is described as involving several categories or time points without a single reduced comparison. A prespecified multiplicity strategy and clear analysis populations would help readers understand how the comparisons were selected and how uncertainty should be interpreted. Such details are not reported in the registry record.

The trial further offers a reminder to distinguish outcome measurement from broader clinical claims. Blood-pressure change is the listed primary endpoint; stroke is part of the study rationale and conditions, not a reported primary outcome result. The statistical record can establish what was intended to be measured, but without posted estimates it cannot establish the magnitude or precision of the blood-pressure comparison or a downstream effect on stroke.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several trial-specific details needed to assess the design and results are not reported in the registry record. The primary and secondary outcome estimates, their dispersion, and inferential comparisons are absent from the record. The primary endpoint is noted as having several categories or time points and not being reduced to one comparison, which leaves the precise contrast for interpretation unclear.

The record does not report detailed eligibility criteria, the randomization procedure, allocation concealment, the allocation ratio, or who knew assignment beyond the masking designation of none. It does not describe the message content or schedule, the health information given to the comparator group, or other co-interventions. These gaps make it difficult to reproduce or precisely characterize the intervention contrast.

Analysis details are also not reported: the statistical model, analysis population, baseline adjustment, handling of missing measurements, and multiplicity strategy. The registry record does not say how many participants had outcome measurements or whether the analysis followed assignment. The enrollment entry alone cannot answer those questions.

The serious-event entries list zero events in each group, but death counts are not reported in the registry record, and details of safety ascertainment are absent. Finally, the endpoint is blood-pressure change over baseline to 6 months; the record does not report a stroke outcome result. These limitations restrict both the statistical interpretation of the blood-pressure comparison and any broader inference about health outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Community Study to Reduce High Blood Pressure Through Text Messaging (REACH OUT) — NCT02664610.
• Registry record last updated 2023-06-05; status last verified 2023-05.
• Results first posted 2017-07-17.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT02664610, titled “Community Study to Reduce High Blood Pressure Through Text Messaging (REACH OUT),” is recorded as a completed randomized, unmasked, parallel-group behavioral study sponsored by University of Michigan. Enrollment is listed as 94. The study took place in an urban African American community in Flint, Michigan; its recorded start was 2014-02 and primary completion was 2015-04.

The intervention was text messaging for participants with high blood pressure, compared with health information without text messages. The primary outcome was mean change in systolic blood pressure from baseline to 6 months, and mean change in diastolic blood pressure was secondary. Numerical outcome results and detailed analysis methods are not reported in the registry record. The recorded adverse-event counts are zero in both groups; deaths are not reported in the registry record.