Jump Start Shared Medical Appointments for Diabetes With Weight Management: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Jump Start Shared Medical Appointments for Diabetes With Weight Management (NCT01973972), a randomized na study. The primary outcome is Hemoglobin A1c.

2. Clinical Question

The study also listed hypoglycemic events, medication effect score, weight, and estimated costs of the intervention strategies as secondary outcomes. Numeric summaries are posted for medication effect score and weight. Results for hypoglycemic events and estimated costs are not reported in the registry record. The record identifies diabetes as the condition and the VA Office of Research and Development as sponsor.

3. Trial Design

This was a randomized, parallel-group trial with no masking. The record marks the phase as NA. Enrollment was 263, and the study status is completed. The recorded start date is 2014-12-12 and the primary completion date is 2018-07-31. These registry entries describe the design and timeline but do not, on their own, establish how participants were recruited, how randomization was implemented, or how outcome assessors handled treatment knowledge; those details are not reported in the registry record.

The two groups received different schedules of group-based care over 48 weeks. WM/SMA combined weight management and diabetes management, while SMA focused on diabetes management. This is an active-comparator design: both groups were assigned a program of shared medical appointments, and the primary contrast concerns adding the weight-management component to that approach. It does not directly estimate the effect of either program against no program or against an unspecified usual-care condition.

The posted primary outcome is mean hemoglobin A1c at 48 weeks, reported as a continuous measure with standard deviations. The outcome summaries include 127 participants in WM/SMA and 136 in SMA. The posted primary comparison is an unadjusted mean difference. The record does not report a separate statistical analysis plan, a description of the analysis population, or details of how missing outcome values were handled. It also does not report the trial's original sample-size justification or the assumptions used when planning enrollment.

The registry lists secondary outcomes related to hypoglycemic events, medication effect, weight, and estimated intervention costs. The available posted numeric secondary summaries concern medication effect score and weight. Inferences from those results should be distinguished from the primary endpoint and treated in light of the absence of reported multiplicity procedures and analysis details.

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 Hemoglobin A1c, measured over 48 weeks.

The primary endpoint was mean hemoglobin A1c at 48 weeks, expressed as a percentage of glycosylated hemoglobin. The registry describes it as a measure of glycemic control. Hemoglobin A1c is used in clinical research because it provides a continuous measure related to blood glucose over time, rather than recording a single glucose reading. As a continuous outcome, it can be summarized by a group mean and standard deviation and compared using a difference in means.

The posted means were 8.2 for WM/SMA and 8.3 for SMA. The reported mean difference, defined as SMA minus WM/SMA, was 0.1. The endpoint is measured at the end of the recorded 48-week program, so this comparison addresses the groups' reported values at that time point. It does not, by itself, describe how either group's outcome changed from its starting value; baseline endpoint values and a change-from-baseline analysis are not reported in the registry record.

Continuous measures preserve information across the range of observed values, but a group mean does not show the full distribution of individual outcomes. The standard deviations add information about variability within each group. Interpretation should therefore consider both the estimated difference and its uncertainty, rather than treating the mean alone as a complete description of participants' outcomes.

7. Results Posted in the Registry

• Shared Medical Appointments (SMA): mean 8.30 versus 8.20 on control; difference 0.10 (95% CI -0.26 to 0.46), standardized effect d = 0.07; z-test p = 0.591.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Medication Effect Score

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Shared Medical Appointments (SMA): mean 2.70 versus 2.20 on control; difference 0.50 (95% CI 0.07 to 0.93), standardized effect d = 0.28; z-test p = 0.021.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Shared Medical Appointments (SMA) than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Weight

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Shared Medical Appointments (SMA): mean 108.00 versus 104.30 on control; difference 3.70 (95% CI -1.12 to 8.52), standardized effect d = 0.19; z-test p = 0.132.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Shared Medical Appointments (SMA) and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes offer a broader view of measures the study intended to examine, but the posted numeric evidence is incomplete. The registry lists hypoglycemic events, medication effect score, weight, and estimated costs of intervention strategies. Numeric arm summaries and unadjusted comparisons are posted for medication effect score and weight; numeric results for hypoglycemic events and estimated costs are not reported in the registry record.

Across the two secondary measures with posted numeric summaries, the estimated directions are not identical in their implications for interpretation: the medication effect score comparison has an unadjusted p-value of 0.021, while the weight comparison has an unadjusted p-value of 0.132 and a confidence interval that crosses zero. These results do not change the primary hemoglobin A1c finding. Secondary measures address different aspects of the program and should not be treated as substitutes for the primary endpoint.

Multiplicity matters because testing several outcomes creates more opportunities for a low unadjusted p-value to occur even when none of the underlying effects is present. General explanation: adjustment procedures can control the overall risk of false-positive findings across a family of tests, but the registry does not report such a procedure. The record also does not report a hierarchy specifying which secondary outcome would be confirmatory. Accordingly, an isolated unadjusted secondary result carries less evidential weight than a result from a prespecified, multiplicity-controlled analysis.

The secondary findings are best treated as descriptive or hypothesis-generating evidence. Their interpretation is further limited by the absence of reported analysis details, missing-data methods, and a complete numeric account for every listed outcome. They can inform questions for future research, but they do not establish a consistent pattern across all secondary outcomes or resolve uncertainty in the primary comparison.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Hypoglycemic Events
• Medication Effect Score
• Weight
• Estimated Costs of Intervention Strategies

9. Statistical Interpretation

10. Statistical Methods Explained

Comparing group means. Hemoglobin A1c is a continuous outcome, and the registry reports a mean for each randomized group. A mean difference subtracts one group mean from the other according to a stated direction. Here, the direction is SMA minus WM/SMA: the SMA mean of 8.3 is compared with the WM/SMA mean of 8.2, and the reported difference is 0.1. A positive estimate therefore points toward a higher observed mean in SMA, while a negative estimate would point toward a higher observed mean in WM/SMA. The sign describes direction, not the importance of the difference.

Standard deviations and standard errors. A standard deviation describes how spread out individual observations are around a group mean. The reported primary standard deviations are 1.6 for WM/SMA and 1.4 for SMA. A standard error describes the uncertainty in an estimated statistic, such as a group mean; it is not another measure of individual variation. Standard errors for the group means are reported as 0.142 and 0.12. General explanation: standard errors are commonly used to construct confidence intervals and test hypotheses. The posted difference uses the group means and their sampling uncertainty to characterize the between-group estimate.

Confidence intervals. A confidence interval communicates uncertainty around an estimate. In general, a 95% confidence interval is produced by a method intended to cover the underlying parameter in 95% of repeated studies under its assumptions. It is not a statement that the particular interval has a 95% probability of containing the parameter. For the primary comparison, the posted interval includes zero. This means the data do not distinguish the observed estimate from no difference at the conventional level associated with that interval. The interval also includes values in both directions, so its interpretation should not be reduced to the point estimate alone.

Unadjusted p-values. The primary unadjusted p-value is 0.591. General explanation: a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that null hypothesis and the model assumptions were true. It is not the probability that the null hypothesis is true, and it does not measure the probability that a result occurred by chance. Because this is an unadjusted value, it does not account for testing multiple outcomes or comparisons. The record does not report a multiplicity procedure or adjusted primary or secondary p-values.

What the posted analysis establishes. The registry identifies the comparison as a mean difference and posts group summaries, confidence limits, standard errors, and an unadjusted p-value. It does not report a model description, covariate adjustments, a prespecified analysis plan, or a named analysis population. The posted comparison should therefore be interpreted as an unadjusted summary rather than attributed to an unreported model. The registry record also does not report whether analyses followed intention-to-treat principles, how participants with missing endpoint data were handled, or whether any sensitivity analyses were performed.

Why variability matters. Differences between group means are interpreted against the variability of individual measurements and the amount of information in each group. A small mean difference can be estimated imprecisely when variability is substantial or the analyzed groups are limited in size. Conversely, a narrow interval indicates greater precision under the analysis assumptions. General explanation: standard deviations describe observed dispersion, whereas confidence intervals describe uncertainty about an estimate; the two answer related but different questions. The posted primary interval is wide enough to include effects in either direction, so the exact between-group difference is uncertain.

Over-dispersion and model choice. General explanation: for count outcomes, over-dispersion occurs when variability exceeds what a simple count model expects. It can make standard errors too small if the model does not allow for the extra variability. The primary endpoint is continuous, not a count, and the registry does not report a count-model analysis for the listed hypoglycemic events. The event definition, event-level data, and any model for those events are not reported in the registry record. It would therefore be inappropriate to infer an over-dispersion adjustment or a particular count model from the posted information.

Planning calculations. The sample-size illustrations use the observed effect as a reference and show participant requirements per arm for specified fractions of that effect. These are planning calculations, not outcomes from the randomized comparison. General explanation: power is the probability that a study will detect a specified effect under stated assumptions if that effect is present. The illustrations are sensitive to their assumptions, including effect size, significance level, allocation, and approximation method. They do not establish the power of the completed trial or reveal the original design rationale, which is not reported in the registry record.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data locate the underlying group difference. The primary estimate is a mean difference of 0.1, while its 95% confidence interval extends across zero and includes values on both sides. This interval indicates that the direction and size of the difference remain uncertain. The unadjusted p-value of 0.591 is consistent with the interval's failure to distinguish the estimate from no difference under the posted analysis.

The group means are accompanied by standard deviations of 1.6 for WM/SMA and 1.4 for SMA. These describe participant-level spread, not the precision of the estimated difference. The confidence interval is the more direct summary of uncertainty about the comparison. It is not appropriate to interpret the small point estimate as proof of equivalence: an equivalence conclusion would require a prespecified equivalence margin and an analysis designed to assess it, neither of which is reported in the registry record.

Precision also depends on what the analysis includes. The registry does not report handling of missing data, adjusted analyses, or an analysis population. If the posted endpoint summaries omit participants or rely on assumptions about unobserved outcomes, those details would affect interpretation, but they are not reported in the registry record. The interval quantifies uncertainty under the analysis used; it cannot resolve uncertainty arising from unreported design or data-handling choices.

The confidence interval does not address whether a difference would be clinically important. The registry record does not give a threshold for a meaningful hemoglobin A1c difference. The estimate and its interval should therefore be read as statistical evidence about the reported group means, not as a stand-alone judgment about clinical relevance.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total participants and not total events. The listed outcomes are continuous measures, and the planning illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It sets the effect to detect at the stated fraction of the observed effect. These are the assumptions for the posted planning illustration; the trial's original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the estimated number of participants required in each arm for an 80% chance of detecting the specified effect under those assumptions. The 90% power column gives the corresponding per-arm requirement for a 90% chance. Power is conditional on the assumed effect and analysis framework; it is not a guarantee that a study will detect an effect or that a result will be important.

Each row changes the effect used for planning. When the target effect is smaller, more participants are needed in each arm to distinguish it from random variation under the same assumptions. The figures for 75% and 50% of the observed effect are therefore larger than the figures based on 100% of that effect. The curve follows this same relationship between the effect chosen and the planning requirement. The displayed values are planning illustrations, not observed power for the completed trial.

These calculations should not be mistaken for the enrollment target that guided the original study. The registry does not report that target's statistical assumptions, nor does the planning exercise account for any unreported features of the trial design or analysis. It is best read as a hypothetical guide to how sample requirements vary with the effect selected, power level, and stated planning assumptions.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.100; pooled standard deviation σ = 1.500.
2. n = 2 × (1.96 + 0.842)² × 1.500² / 0.100² = 3,531.5, rounded up to 3,532 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.100000000000001                      # observed difference in means
sigma <- 1.499885053067                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1973972)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 3,532 (80% power), 4,728 (90% power)
 75% of observed effect: n per arm = 6,279 (80% power), 8,405 (90% power)
 50% of observed effect: n per arm = 14,126 (80% power), 18,911 (90% power)
power.t.test: 3532.4 
Simulated power at n = 3,532 per arm: 0.803 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and several secondary outcomes, but the number and structure of formal hypothesis tests are not described. No statistical analysis plan, multiplicity adjustment, or prespecified hierarchy among secondary outcomes is reported in the registry record. The posted secondary p-values are unadjusted. When multiple outcomes are examined, the chance of at least one apparently unusual result can increase; therefore, unadjusted secondary findings should be interpreted cautiously rather than as definitive evidence.

The registry record does not report the amount or pattern of missing data, the method used to handle missing outcome measurements, or whether any sensitivity analyses assessed the impact of missingness. It also does not specify whether the primary comparison used an intention-to-treat population, a per-protocol population, or another analysis set. Without these details, readers cannot assess whether the posted summaries include all randomized participants or whether the analysis depends on assumptions about unavailable measurements.

The group summaries identify 127 participants for WM/SMA and 136 for SMA for the primary outcome. Those reported group sizes do not, by themselves, describe participant flow, reasons for non-observation, or the number contributing to every analysis. Such details are not reported in the registry record.

The record posts an unadjusted primary mean comparison and no reported analyses beyond those posted summaries. It does not explain whether the analysis was selected before outcomes were observed, whether covariates were considered, or whether interim analyses were conducted. These elements are not reported in the registry record and should not be inferred. Their absence limits the ability to evaluate the risk of selective reporting and the robustness of the analysis, although it does not by itself establish that any particular problem occurred.

15. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: sepsis (1.6%), muscle pain (1.6%), joint replacement (1.6%), urologic surgery (1.6%), hypotension (1.6%).

The safety record lists serious adverse events for 27 of 127 participants in WM/SMA and 27 of 136 participants in SMA. Other adverse events are listed for 12 participants in WM/SMA and 9 in SMA. The record lists 2 deaths in each group. These are counts recorded for the respective groups; they do not, by themselves, show whether events were caused by the assigned program or whether the groups differed in risk.

The serious-event terms listed most prominently are sepsis, muscle pain, joint replacement, urologic surgery, hypotension, and stroke, each recorded as 1.6%. These terms describe reported events, not an assessment of causality. The registry does not provide additional context about timing, severity classifications beyond the serious-event category, relatedness to intervention, or event-level participant histories. Those details are not reported in the registry record.

Safety counts should be read alongside the study's design and reporting limits. They are not a substitute for a detailed safety analysis, and the difference in group sizes should be kept in mind when comparing raw counts. No conclusion about relative safety or treatment effects follows from the counts alone.

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

The primary result is a small observed difference in mean hemoglobin A1c at 48 weeks: the SMA mean was 8.3 and the WM/SMA mean was 8.2, with a reported SMA-minus-WM/SMA difference of 0.1. The confidence interval includes zero, and the unadjusted p-value is 0.591. The posted data therefore do not precisely establish the direction or size of a difference between these two groups at the recorded time point.

This is not evidence that the programs are equivalent. Equivalence requires a prespecified margin defining how much difference would be considered acceptably small and an analysis designed to test that question. Such a margin and analysis are not reported in the registry record. Nor does a non-significant result prove that there is no effect; it indicates that the posted analysis did not clearly distinguish the estimate from no difference.

The estimate applies to the comparison of two group-appointment programs, one of which included weight management. It is not a comparison with no treatment, and it does not isolate every component of either program. The recorded outcome is a group mean at 48 weeks; it does not show individual responses, longer-term outcomes, or change from baseline. Those additional results are not reported in the registry record.

Secondary results may help describe other measures, but the posted numeric summaries cover only medication effect score and weight among the listed secondary outcomes. Their unadjusted nature and the absence of a reported multiplicity plan mean they should not override the primary result or be treated as conclusive on their own. The safety counts likewise describe recorded events without establishing causation.

Overall, the registry results provide an estimate and an indication of its uncertainty, rather than a definitive answer about clinical benefit, harm, or equivalence. Further interpretation depends on design and analysis details—including missing-data handling and the analysis population—that are not reported in the registry record.

17. Why This Trial Matters Statistically

This trial is statistically informative because it compares an added weight-management component with an active program of shared medical appointments, rather than using a no-care comparator. That distinction makes the estimated contrast specific: it concerns the difference between the recorded WM/SMA and SMA programs. Readers should not interpret it as the effect of shared appointments themselves relative to another form of care.

The primary endpoint is continuous and has posted group means, standard deviations, a mean difference, and a confidence interval. Taken together, these permit a more complete reading than a p-value alone: the estimate is 0.1, the interval crosses zero, and the p-value is 0.591. This makes the uncertainty and scale of the observed contrast visible without converting statistical evidence into a claim of clinical importance.

The record also illustrates why secondary outcomes need a different evidential status from a primary endpoint. Several outcomes are listed, but multiplicity procedures and a hierarchy are not reported. An unadjusted finding on a secondary measure can be useful for generating questions while remaining less conclusive than a prespecified, controlled analysis.

Finally, the record's omissions are consequential for statistical interpretation. Missing-data procedures, analysis populations, and the original sample-size rationale are not reported. The planning illustration can show how sample requirements change under stated assumptions, but it cannot reconstruct the original design or establish the completed study's observed power. Distinguishing what the posted estimates show from what the record does not document is essential to a measured reading of the evidence.

18. 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 limitations specific to this registry record constrain interpretation. The primary outcome is reported at 48 weeks, but baseline hemoglobin A1c values and a change-from-baseline analysis are not reported in the registry record. The posted group means therefore describe the recorded endpoint, not within-person change over the study period.

The record does not give detailed eligibility criteria, participant characteristics, recruitment methods, or information about the delivery and uptake of the group programs. It describes the intended visit schedules, but does not report attendance, adherence, or whether participants received additional care that could affect outcomes. These omissions limit assessment of how closely the recorded programs were implemented and to whom the findings might apply.

For statistical interpretation, the registry does not report the analysis population, missing-data methods, covariate adjustment, interim analyses, or a complete analysis plan. It also does not report multiplicity adjustment for the secondary outcomes. The available comparisons are unadjusted, so they should not be described as adjusted effects or as definitive confirmatory results.

Although four secondary outcome categories are listed, numeric results are not reported for hypoglycemic events or estimated costs in the record. The safety summary provides event counts and selected serious-event terms but not detailed timing, relatedness, or event-level descriptions. These limits prevent a fuller evaluation of those outcomes.

The sample-size illustrations are based on the observed effect and stated planning assumptions, not the trial's original design rationale. They cannot establish whether the completed trial was adequately sized for its intended question. The registry also does not report longer-term follow-up or subgroup analyses, so conclusions should remain tied to the posted 48-week comparison.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Jump Start Shared Medical Appointments for Diabetes With Weight Management — NCT01973972.
• Registry record last updated 2023-07-28; status last verified 2023-07.
• Results first posted 2019-09-16.
• 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.

22. Record Summary

NCT01973972, titled “Jump Start Shared Medical Appointments for Diabetes With Weight Management,” is recorded as a completed, randomized, unmasked, parallel-group trial sponsored by the VA Office of Research and Development. The condition is diabetes, and enrollment was 263. The recorded study start date was 2014-12-12, with primary completion on 2018-07-31.

The primary outcome was mean hemoglobin A1c at 48 weeks. The posted WM/SMA and SMA means were 8.2 and 8.3, respectively; the reported SMA-minus-WM/SMA difference was 0.1, with an unadjusted p-value of 0.591 and an interval that includes zero. Numeric secondary comparisons are posted for medication effect score and weight. The registry lists additional secondary outcomes, but numeric results for hypoglycemic events and estimated costs are not reported in the registry record.

The record does not report the original sample-size justification, missing-data methods, analysis population, or multiplicity procedures. These gaps should inform interpretation of the posted estimates and secondary findings.