Improving Medication Adherence Among Underserved Patients With Type 2 Diabetes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving Medication Adherence Among Underserved Patients With Type 2 Diabetes (NCT02409329), a randomized na study. The primary outcome is Change in Glycemic Control as Indicated by Hemoglobin A1c (HbA1c).

2. Clinical Question

3. Trial Design

This was a randomized, single-masked, parallel-group study of behavioral interventions for adults with type 2 diabetes. The registry lists enrollment of 512 and a completed study status. The recorded study start was 2016-05-23, and primary completion was 2019-06-04. The phase is listed as NA.

The registry describes three conditions: REACH, REACH + FAMS, and Helpline and A1c Results. REACH involved tailored text messages for 12 months. The REACH + FAMS condition added monthly phone coaching, messages supporting a goal set during coaching, and the option for a family member or support person to receive messages. The full duration description for this condition is not reported in the registry record. The control group was to maintain care as usual, including medical treatment and physician monitoring. All participants were to receive messages about accessing their study A1c results.

The primary outcome comparison combines the REACH and REACH + FAMS groups and compares them with participants not receiving REACH. This is a comparison of the combined intervention conditions with the control condition, not a separate primary comparison of each intervention against control. The registry does not report the rationale for combining the two intervention groups or details of the randomization procedure beyond identifying allocation as randomized.

Single masking is recorded, but who was masked and how masking was maintained are not reported in the registry record. Further details about recruitment, eligibility, allocation concealment, adherence to assigned interventions, and protocol deviations are also not reported in the registry record. These details would help readers assess how participants entered and remained in each condition.

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.

Before assignment: 6 participants were administratively withdrawn prior to randomization; 5 were unreachable during a pre-determined run-in period after enrollment, 1 behaved inappropriately with a research assistant during enrollment

Overall Study

Analysis population for the primary outcome, as defined in the registry: We compared participants receiving the REACH intervention (combining REACH and REACH + FAMS) with participants not receiving REACH (in condition Helpline and A1c Results).

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 Change in Glycemic Control as Indicated by Hemoglobin A1c (HbA1c), measured over Baseline, 3 months, 6 months, 12 months, 15 months.

The primary endpoint is change in glycemic control, measured by hemoglobin A1c (HbA1c) as a percentage. The registry specifies measurements at baseline, 3 months, 6 months, 12 months and 15 months. Higher HbA1c values indicate worse glycemic control, and the registry describes an improvement of 0.5% as clinically meaningful.

HbA1c is used to assess glycemic control because it provides a measure of glucose control over time rather than a single point-in-time reading. In general, following a continuous outcome across multiple visits can show how its average level changes during follow-up. The registered comparison asks whether that change differs between the combined REACH groups and the group not receiving REACH.

The record identifies the endpoint as a mean and lists standard deviation as its dispersion measure. It does not report group means, mean changes, a between-group effect estimate, confidence intervals, or a p-value for this outcome. Therefore, the direction, size and precision of the observed primary comparison cannot be assessed from the registry record. The 0.5% value is the registry's stated clinical-meaningfulness benchmark; it is not itself a reported study result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous: HbA1c is recorded as a percentage, and the registry identifies the outcome summary as a mean with standard deviation. In general, a mean describes the average value in a group, while a standard deviation describes how dispersed individual measurements are around that average. These summaries answer different questions: the mean describes the group level, and the standard deviation describes variation among participants. Neither by itself gives the uncertainty in a comparison between groups.

The registered primary comparison pools the REACH and REACH + FAMS conditions and contrasts them with Helpline and A1c Results. This defines the groups relevant to the primary question. It does not establish that the two REACH conditions have identical effects. Rather, the stated comparison concerns the combined intervention group as defined in the registry. Separate effects for REACH and REACH + FAMS, and a direct contrast between those conditions, are not reported in the registry record.

Measurements are listed at baseline, 3 months, 6 months, 12 months and 15 months. In general, repeated measurements can be analyzed by comparing changes from baseline, comparing group averages at follow-up while accounting for baseline, or modeling the pattern across visits. These approaches answer related but not identical questions and can produce different estimates. The statistical model, the precise estimand, and the method used to handle correlation among measurements from the same participant are not reported in the registry record.

For a continuous outcome, a treatment contrast might be expressed as a difference in mean change or as a difference between group means at a specified visit. The registry does not provide such an estimate for HbA1c. It also does not report confidence intervals or p-values for the primary outcome. In general, a confidence interval communicates the precision of an estimate, while a p-value evaluates compatibility between the observed data and a specified null hypothesis under the analysis assumptions. Neither measure alone communicates clinical importance; interpretation also depends on the size of the estimate and the clinical context. Here, the registry names 0.5% as a clinically meaningful improvement, but reports no primary effect estimate to evaluate against that reference.

Random allocation is recorded, which describes the intended assignment method. In general, randomization aims to make treatment groups comparable on average with respect to measured and unmeasured baseline characteristics. It does not guarantee that the groups will be identical, and it does not resolve concerns about missing outcome data, departures from assigned treatment, or incomplete follow-up. The registry does not report allocation concealment, baseline comparisons, adherence to assignment, or the analysis population used for the primary outcome.

The registry lists standard deviation as the outcome's dispersion measure, but does not report the observed standard deviations or the number of participants contributing HbA1c data at each visit. It is therefore not possible to assess the variability of the outcome or whether follow-up availability differed across groups. Details on missing-data methods, sensitivity analyses, and assumptions about participants with unobserved measurements are not reported in the registry record.

A planning illustration is described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The listed approach uses the stated fraction of the observed effect as the target effect; for non-time-to-event outcomes, results are expressed as participants per arm for 80% power or another listed power level. These are planning illustrations, not observed power and not the trial's own sample-size justification. The registry does not report a sample-size justification, and no numerical planning results are reported in the registry record for this analysis. In general, a planning calculation depends on assumptions about the target effect, variability, significance threshold, allocation and analysis. It does not establish what effect the trial observed or how likely the study was to detect an effect after data collection.

Over-dispersion is a general concern when observed variability is greater than assumed by a model, particularly for outcomes analyzed with distributions that expect a specific relationship between their mean and variance. The primary endpoint is described as a continuous mean with standard deviation; the registry does not state that an over-dispersion adjustment was used or identify the primary analysis model. No specific model diagnostics or model-based corrections are reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is measured at several time points, and the registry lists seven outcome measures and sixteen analyses. It does not report how the analyses were organized, which were confirmatory, or whether any adjustment for multiple comparisons was planned or applied. The registry's primary outcome entry notes that it has several time points and is not reduced to one comparison. Consequently, the record does not identify a single numerical primary contrast that can be interpreted alongside a specified multiplicity procedure.

In general, examining multiple outcomes, time points or contrasts creates more opportunities for chance findings. A multiplicity strategy can define which tests are primary, control an error rate across a family of tests, or distinguish confirmatory from exploratory analyses. The appropriate interpretation depends on the analysis plan and the specific tests performed. Those details are not reported in the registry record, so the degree to which multiplicity affected the reported analyses cannot be assessed.

The registry lists “Change in Self-reported Medication Adherence” twice among secondary outcomes. It does not report whether these entries represent different measures, time points or analyses. The definitions, instruments and results for those entries are not reported in the registry record.

Missing-data handling is also not reported. The outcome schedule includes baseline and follow-up measurements, but the record does not give the number of participants with observed HbA1c at each visit, reasons for missingness, or methods used to address missing values. The analysis population—such as whether the primary analysis included all randomized participants or only participants with available data—is not reported in the registry record. In general, missing-data assumptions matter because an analysis of available measurements may differ from one that uses a model or imputation method to account for unobserved values.

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 1% reporting threshold.

The registry reports serious adverse events and other adverse events separately for REACH, REACH + FAMS and Helpline and A1c Results. In the serious adverse event entries, zero affected participants are listed in each group. The other adverse event entries also list zero affected participants in each group. The corresponding numbers at risk are 127 for REACH, 126 for REACH + FAMS and 253 for Helpline and A1c Results.

Deaths are listed separately: 3 for REACH, 2 for REACH + FAMS and 3 for Helpline and A1c Results. These counts should not be treated as serious adverse-event totals; the registry reports them in a distinct field. The list of leading serious-event terms is empty.

These are registry counts, not a causal comparison. The record does not report event timing, event definitions, severity details beyond the serious/non-serious categories, relatedness assessments, or statistical comparisons between groups. In general, zero events recorded in a category does not by itself establish that no risk exists; it describes the events reported for the listed groups and denominators. The counts also do not establish whether an event was caused by an intervention or by other factors.

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

The study was designed to evaluate tailored mobile-phone messaging for adults with type 2 diabetes, comparing a combined group receiving REACH with a control group that did not receive REACH. The primary endpoint was change in HbA1c, measured at baseline and several follow-up times. The registry also describes an enhanced REACH condition that adds coaching and family-support options.

What the registry does not establish is the size or direction of the primary outcome result. Numerical HbA1c findings, an estimate of the between-group contrast, and measures of uncertainty are not reported in the registry record. It is therefore not possible to determine from this record whether the intervention groups had different HbA1c changes, how precise any difference was, or whether an observed change met the registry's stated clinical-meaningfulness reference of 0.5%.

The primary comparison combines REACH and REACH + FAMS. It cannot, on its own, separate the effect of tailored messages from the additional FAMS components. Nor does the registry provide a reported direct comparison between these two intervention conditions. The intervention descriptions explain what was planned, but do not establish how consistently participants received or engaged with the components.

The safety entries report no affected participants in the serious or other adverse event categories, while recording deaths separately for each group. These entries do not provide a causal assessment, detailed event descriptions or comparative safety analysis. The registry record also lacks information needed to evaluate missing outcome data, the primary analysis population, and the statistical model.

In general, a trial's design and outcome definitions describe the question it set out to answer; numerical estimates and their uncertainty are needed to understand what the collected data show. Without the primary numerical results, interpretation should remain limited to the study's registered aims, design and reported event counts. The record does not support a conclusion about whether the intervention changed glycemic control or medication adherence.

13. Why This Trial Matters Statistically

This trial is statistically notable for its group definition and repeated outcome schedule. The registered primary question combines two intervention conditions—REACH and REACH + FAMS—and compares that combined group with participants not receiving REACH. This defines the primary contrast, but it does not isolate the contribution of coaching or family-support components. A reader should distinguish the intervention's overall registered comparison from questions about which component may account for a result.

The primary endpoint is measured at baseline and multiple follow-up times. In general, repeated measurements contain information about both the level of an outcome and its course over time. The choice of analysis determines how measurements are combined and what contrast is estimated. Because the statistical model and numerical results are not reported in the registry record, the specific longitudinal interpretation cannot be assessed.

The registry also describes a clinical-meaningfulness benchmark for HbA1c, which is conceptually distinct from statistical precision. A result can be estimated precisely without being clinically meaningful, or be potentially important but estimated imprecisely. Assessing that distinction requires an effect estimate and uncertainty interval, neither of which is reported for the primary outcome.

Finally, a study can be carefully randomized and still require clear reporting of follow-up, missing data, analysis populations and multiplicity. Those details allow readers to understand how the planned comparison became a reported estimate and how robust it may be. Their absence from the registry record limits statistical interpretation, independent of the intervention's subject matter.

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 main limitation for interpreting this trial is that numerical primary HbA1c results are not reported in the registry record. Group means, changes, between-group estimates, confidence intervals and p-values are not available. Without them, neither the magnitude and direction of the primary comparison nor its precision can be assessed.

The primary comparison combines REACH and REACH + FAMS, so it does not separately identify the contribution of the additional coaching and support-person components. Separate arm results and a direct comparison between the two intervention groups are not reported. The description of the REACH + FAMS duration is incomplete in the registry record.

The outcome was scheduled across multiple time points, but the analysis model and the approach to repeated measurements are not reported. The registry also does not report the number of participants with outcome data at each visit, missing-data methods, the primary analysis population, or sensitivity analyses. These omissions prevent assessment of how incomplete follow-up may have affected the estimated comparison.

Although the study is recorded as randomized and single-masked, the masking procedure and the identity of the masked parties are not reported. The allocation procedure beyond the randomized designation, adherence to assigned interventions, and protocol deviations are also not reported in the registry record.

The record lists seven outcome measures and sixteen analyses but does not describe a multiplicity plan or distinguish confirmatory from exploratory analyses. It also does not report a sample-size justification. The stated planning illustration is based on an observed effect and specified assumptions, but does not supply the trial's original design rationale. These reporting gaps limit assessment of the analysis strategy and the strength of conclusions that could be drawn from the trial results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Improving Medication Adherence Among Underserved Patients With Type 2 Diabetes — NCT02409329.
• Registry record last updated 2020-08-17; status last verified 2020-08.
• Results first posted 2020-08-17.
• 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

NCT02409329 is a completed randomized, single-masked, parallel-group behavioral study sponsored by Vanderbilt University Medical Center. It enrolled 512 participants with type 2 diabetes. The recorded start date is 2016-05-23, and primary completion is listed as 2019-06-04.

The study compared REACH text messaging, REACH plus FAMS support, and a Helpline and A1c Results control condition. Its primary outcome was change in HbA1c, measured at baseline, 3 months, 6 months, 12 months and 15 months. The primary comparison combines the REACH conditions and contrasts them with the group not receiving REACH.

The registry record does not report numerical primary outcome results or the statistical model used. It lists zero participants affected by serious and other adverse events in each group, and separately records deaths as 3, 2 and 3 across the three groups.