The Smart Hypertension Control Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Smart Hypertension Control Study (NCT03288142), a randomized na study. The primary outcome is Blood Pressure at 6 Months.

2. Clinical Question

3. Trial Design

The Smart Hypertension Control Study was a randomized, parallel-group trial. The registry record lists masking as none, meaning the study is recorded as unmasked. It lists enrollment as 333 and the status as completed. The phase is recorded as NA. The sponsor is Northwestern University.

The study compared a hypertension coaching application plus a home blood pressure monitoring device with a control condition described as a tracking application and the home monitor. The intervention arm description says participants received the control interventions as well as Lark HTN Pro. The control description mentions a home monitor, instructions in its use at the baseline study visit, and an information sheet. Full descriptions of both arms are not reported in the registry record.

The registry dates the study start to 2017-09-21 and primary completion to 2019-04-28. The stated goal was to investigate the effects of the personal control program on blood pressure, blood pressure self-management behaviors, and healthy lifestyle behaviors among adults with hypertension. The record lists secondary outcomes concerning medication use and changes, health system contacts, home blood pressure measurement, confidence in controlling high blood pressure, BMI, and diet quality.

Randomization is a design feature intended to support fair comparison of groups by assigning participants through a chance-based process. General explanation: random assignment does not itself establish that the groups were similar in every characteristic, nor does it show what happened to the outcomes. The registry record does not report allocation concealment, the method used to generate assignments, or participant flow after enrollment. These details should not be inferred from the word “randomized.”

Because the record identifies no masking, it does not describe masked participants or study personnel. This matters when interpreting outcomes that can be influenced by awareness of group assignment, but the record does not provide enough detail to assess whether or how such influence affected measurement or conduct.

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

Reasons for not completing this period:

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.

Population: 166 participants contributed data for the hypertension coaching application arm of the study. 167 participants from the tracking application arm contributed data to the study. Overall number of participants is 333. 22 participants from intervention arm were excluded from analyses for various reasons leaving 144 participants for analyses.1 missing data and 14 participants were lost to follow up and were excluded from analyses in the control arm which leaves us with 153 participants for analyses.

6. Primary Endpoint

The registry lists the primary outcome as Blood Pressure at 6 Months, measured over 6 months.

The primary outcome is described as blood pressure at 6 months, with the measurement summarized as a mean and standard deviation. Blood pressure is a continuous measure: a mean describes the central level of observations in a group, while a standard deviation describes how much observations vary around that mean. The registry record gives the unit as mmHG.

The outcome’s timeframe is 6 months. Comparing group means at a stated follow-up can describe how the groups’ measured blood pressure levels differ at that time. It does not, by itself, describe changes from baseline, unless a change-from-baseline analysis is specified. The registry record does not specify whether the primary measure is systolic blood pressure, diastolic blood pressure, or another blood pressure summary. It also does not state whether the intended estimate is an endpoint value, a change, or an adjusted comparison.

Blood pressure is relevant to the stated study goal, which concerns blood pressure and self-management among adults with hypertension. That rationale does not fill in the missing outcome definition or establish what the trial found. The registry record does not provide a single primary comparison, its group means, an estimated difference, a confidence interval, or a test result. It therefore does not support a quantitative interpretation of the primary outcome’s direction, size, or precision.

General explanation: reporting a mean alongside a standard deviation helps describe the distribution of a continuous outcome, but the standard deviation is not the same as the uncertainty in the estimated group mean or in a contrast between groups. An estimate of a contrast and its uncertainty would be needed to assess how compatible the posted data are with different possible group differences.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the outcome summary mean?

The primary outcome is specified as a mean with standard deviation, a conventional way to describe a continuous measure. The mean is the arithmetic average of observed measurements in the group being summarized. The standard deviation describes the spread of individual measurements around that average. Neither quantity alone is a between-group effect estimate. To interpret the comparison, the group summaries or a directly estimated contrast would be needed.

The registry record specifies the timeframe as 6 months and the unit as mmHG. It does not identify the particular blood pressure category, explain how measurements were collected or combined, or state whether the analysis concerns follow-up values or change from baseline. These details are important because they define what the estimate represents. They are not reported in the registry record.

What would an effect estimate and interval add?

General explanation: an effect estimate expresses the contrast between groups in a defined way. For a continuous outcome, it might be a difference in means, but the registry record does not report that such an estimate was used for this trial. A confidence interval conveys uncertainty about an estimate under a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, but precision does not by itself establish importance or remove possible bias.

A p-value, if reported, would address compatibility between the observed data and a stated null model under the assumptions of the test. It would not measure the probability that the null hypothesis is true, and it would not describe the size of an effect. No p-value or testing method is reported for the primary comparison in the registry record. There is therefore no basis for describing statistical significance.

What can randomization tell a reader?

General explanation: random assignment is used to create groups whose differences, on average over repeated assignments, are not systematically determined by participant characteristics. It can support a causal comparison when assignment, follow-up, outcome measurement, and analysis are implemented and reported appropriately. The record identifies the allocation as randomized and the model as parallel, but does not report the assignment procedure, concealment, deviations from assignment, or analysis details. The design label alone cannot establish how these issues were handled.

The record lists masking as none. General explanation: when treatment assignment is known, expectations or behavior can affect some aspects of participation, measurement, or care. The extent of any such influence depends on the outcome and conduct of the trial. The record does not describe procedures to limit or evaluate it, so no trial-specific conclusion about its effect is justified.

How should the planning assumptions be read?

The registry record describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not reported trial findings. The record does not provide a single primary comparison or an observed effect on which to base a quantitative interpretation of such planning illustrations.

General explanation: a sample-size calculation asks what enrollment would be needed under specified assumptions to have a chosen chance of detecting an effect of a chosen size by a chosen statistical procedure. Such a calculation is conditional on those assumptions. It is not an estimate of the probability that this completed trial found a real effect. Sample sizes in a planning illustration are not observed power, and they do not substitute for the trial’s effect estimate and uncertainty.

The record specifies that non-time-to-event planning figures are expressed as participants per arm, while time-to-event figures are expressed as total events. This primary outcome is described as a continuous mean, not a time-to-event outcome. However, no numerical planning figures or observed primary effect are reported in the registry record for a single comparison, so there is no trial-specific sample-size value to interpret.

Why do analysis details matter?

General explanation: a statistical analysis plan defines the outcome, contrast, model, handling of missing observations, and other decisions that shape an estimate. Pre-specification can reduce the risk that results are selected or interpreted after seeing the data. The registry record does not report the analysis plan, adjustment variables, interim analyses, or sample-size justification. Their absence from the record should not be replaced with assumptions about what investigators planned or did.

The outcome is described as continuous, but the statistical model and assumptions are not reported. General explanation: a model can account for the structure of data and can produce an estimate with uncertainty, but its appropriateness depends on the outcome and design. The record does not state whether an unadjusted or adjusted analysis was intended, whether repeated measurements were modeled, or how distributional assumptions were assessed. No method can be attributed to this trial on the basis of the reported registry information alone.

There is also no reported primary analysis result to recalculate from summary statistics. Consequently, no recalculated comparison, confidence interval, or test result can be offered. The central methodological limitation is not that a particular method is known to be inadequate; it is that the registry record does not report enough detail to identify and evaluate the method used.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 12 outcome measures, including blood pressure and secondary outcomes related to medication use, health system contacts, home blood pressure measurement, self-efficacy, BMI, and diet quality. It lists zero analyses. The record does not report how many outcomes were tested, which results were prioritized, or whether any multiplicity procedure was planned or applied.

General explanation: when investigators make many statistical comparisons, the chance of obtaining at least one apparently notable result by chance can increase. Methods such as pre-specifying a primary comparison or adjusting for multiple testing can help address this issue, but the appropriate approach depends on the analysis plan. The registry record does not describe a plan for multiplicity, so it is not possible to judge how multiple outcomes or blood pressure categories and time points were handled.

Missing-data methods are also not reported. The record does not state how many participants had outcome measurements at 6 months, whether reasons for missing measurements were recorded, or how any missing values were treated. It does not identify an analysis population, such as all randomized participants or participants with observed outcome data. The safety risk counts do not resolve these questions because they are not reported as primary-outcome analysis counts.

General explanation: missing data can affect interpretation when the likelihood of an outcome being observed is related to participant characteristics or outcomes. Different assumptions and methods can produce different estimates. Without the amount, pattern, and handling of missing outcome data, the robustness of any primary comparison cannot be assessed. These features are not reported in the registry record.

11. Safety Results

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

Deaths

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, zero other adverse events, and zero deaths in each group. The risk counts are 166 for the intervention group and 167 for the control group. These are the denominators recorded for the safety figures; they should not be assumed to be the numbers contributing to the blood pressure outcome analysis.

These entries describe what the registry record reports. They do not establish that no adverse events occurred outside the categories or reporting period captured by the record, and they do not describe how events were collected, defined, or adjudicated. The record provides no serious adverse event terms. No further safety-event detail is reported in the registry record.

General explanation: a zero count in a recorded category is not proof that an intervention has no risks. Safety interpretation depends on the size and follow-up of the group, the event definitions, how completely events were ascertained, and the uncertainty around the observed counts. The registry record does not provide an analysis of comparative safety or an uncertainty estimate for these figures.

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

The registry record establishes that a randomized, parallel-group study of a smartphone hypertension coaching program and home monitoring was completed. It identifies blood pressure at 6 months as the primary outcome and gives a mean and standard deviation as the intended summary. It also records 333 participants enrolled and lists a set of additional outcomes.

It does not, however, report a single primary comparison or the numerical outcome results needed to describe what the study found about blood pressure. The record does not provide group means, an estimated difference, an interval, or a test result. The direction, magnitude, and precision of a blood pressure contrast therefore cannot be determined from the reported information. The absence of a reported comparison is not evidence of no difference.

The record’s study goal includes blood pressure self-management behaviors and healthy lifestyle behaviors. The named secondary outcomes cover several related topics, but no results for them are reported. Their inclusion in the outcome list does not show whether an outcome changed or whether a group difference was observed.

General explanation: a trial design and an outcome definition describe what researchers intended to study; they do not establish the result. Interpreting results requires estimates, uncertainty, and sufficient detail about outcome measurement and analysis. A statistically detectable difference, if reported, would also need to be distinguished from a difference that is important in practice. No such judgment can be made without the primary results and relevant context.

The safety entries list no serious adverse events, other adverse events, or deaths in either group. Those entries are limited to the categories and denominators recorded and do not support a broad conclusion that the intervention is risk-free. Overall, the record describes the study question and design more clearly than it reports the comparative findings.

13. Why This Trial Matters Statistically

This study is statistically notable as a randomized comparison of a smartphone coaching application plus home blood pressure monitoring against a tracking application and home monitoring. The comparison puts a digital coaching program in a context where both groups are described as receiving a home monitor. That design makes the intended contrast more specific than a comparison of monitoring with no monitoring, although the registry record does not provide enough detail to characterize every component of either arm.

The trial’s stated aim spans blood pressure, self-management behaviors, and healthy lifestyle behaviors. Its outcome list reflects this breadth, including medication-related measures, health system contacts, home measurement, self-efficacy, BMI, and diet quality. This range makes clear why a prespecified primary outcome and transparent reporting of the analysis approach matter: readers need to know which comparison addresses the central question and how the other outcomes are interpreted.

The record identifies a continuous primary outcome at 6 months but does not report one comparison or its results. Statistically, that gap is consequential. Without an estimate and uncertainty, readers cannot distinguish a large, precise contrast from a small or uncertain one, or assess how the result relates to the stated study goal. The trial’s randomized design cannot fill that reporting gap.

General explanation: complete reporting links the design question to a defined outcome, an analysis population, a statistical method, and an estimate with uncertainty. This lets readers assess both the evidence and its limitations. The registry record documents important design features and the planned area of measurement, but does not report enough comparative outcome information to support those steps for the primary question.

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.

The primary outcome is not represented as a single comparison in the registry record. Although it is titled blood pressure at 6 months and described as a mean with standard deviation, the record does not identify the specific blood pressure category or say whether the intended analysis uses follow-up values, change from baseline, or an adjusted comparison. It provides no group summaries or estimated contrast. This prevents trial-specific interpretation of the primary result.

The record does not report the primary analysis population, the number of participants with measurements at 6 months, or missing-data procedures. It also does not report allocation concealment, the method of sequence generation, the full analysis plan, or adjustment methods. These are reporting limitations; they do not establish that the study did or did not use any particular procedure.

The arm descriptions in the registry record do not provide complete detail about the application content or all components of the control condition. The record lists no masking. Without further information about measurement procedures and conduct, the possibility of influences associated with awareness of group assignment cannot be evaluated.

The registry record lists 12 outcome measures and zero analyses, without reporting a multiplicity strategy or results for the secondary outcomes. It also does not give a sample-size justification or interim-analysis information. The planning assumptions described in the record do not supply a numerical estimate for a single primary contrast. These gaps limit assessment of precision, selective emphasis, and the relationship between the design and the reported findings.

Finally, the safety entries are limited to the recorded categories and counts. Definitions, ascertainment procedures, and comparative safety analyses are not reported in the registry record. Each limitation concerns what can be evaluated from the record and should not be treated as proof of a particular flaw in trial conduct.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Smart Hypertension Control Study — NCT03288142.
• Registry record last updated 2022-04-15; status last verified 2022-04.
• Results first posted 2022-04-15.
• 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

The Smart Hypertension Control Study (NCT03288142), sponsored by Northwestern University, is recorded as a completed randomized, parallel-group study with no masking. Enrollment was 333. The registry dates the study start to 2017-09-21 and primary completion to 2019-04-28.

The study compared a hypertension coaching application, identified as Lark HTN Pro, plus a home blood pressure monitoring device with a control condition described as a tracking application and home monitor. The primary outcome is blood pressure at 6 months, summarized as a mean with standard deviation. The registry record does not identify one primary comparison or report its results.

The record lists 12 outcome measures and zero analyses. It does not report the analysis population, missing-data methods, multiplicity approach, or primary effect estimate. Safety entries record zero serious adverse events, zero other adverse events, and zero deaths in both groups, with risk counts of 166 and 167, respectively. These safety entries do not replace comparative outcome results.