Improving Patient-Provider Communication to Reduce Mental Health Disparities: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving Patient-Provider Communication to Reduce Mental Health Disparities (NCT04515771), a randomized na study. The primary outcome is Patient Activation Measure- Mental Health (PAM-MH).

2. Clinical Question

3. Trial Design

The registry describes a randomized, unmasked, crossover study with a planned enrollment of 50. It records the phase as not applicable. The study began on 2020-08-17, reached primary completion on 2022-04-15, and is listed as completed. The sponsor is the VA Office of Research and Development.

Participants were randomized to one of two groups determining when they received PARTNER-MH. The active PARTNER-MH group received the intervention immediately after enrollment and continued usual mental health services. The waitlist control group received usual mental health services and was offered the intervention after the 6-month wait period. Both groups therefore had the opportunity to receive the program, but at different times. The registry also says participants could receive services in addition to their regular mental health treatment.

Participants were asked to complete questionnaires at different timepoints to assess satisfaction with the program and mental health services. Some also completed an interview about their experience. The primary outcome is change in PAM-MH from baseline to 6 months. The primary outcome summaries report 18 participants in each arm. The registry does not report the full sequence of assessment times, the length of follow-up after the waitlist group received the program, or how the crossover label was reflected in the primary comparison. It also does not report the original design assumptions or a detailed account of the randomization procedure.

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.

Period 1: 6 Month Randomized Period

Reasons for not completing this period:

Period 2. 6 Month Waitlist Crossover

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.

6. Primary Endpoint

The registry lists the primary outcome as Patient Activation Measure- Mental Health (PAM-MH), measured over Change from Baseline to 6 months.

The primary endpoint is change from baseline to 6 months in the Patient Activation Measure-Mental Health (PAM-MH). It is a 13-item questionnaire about a person's perceived ability to manage illness and health behaviors. Each item uses a 4-point response scale, and the responses are converted by Rasch analysis to an activation score on a 100-point scale. The registry states that higher activation scores indicate a higher level of patient activation.

A change score expresses how much the recorded score moved between the baseline assessment and the 6-month assessment. The posted group summaries report the mean change and standard deviation for each arm. Comparing mean changes gives a direct summary of the average difference between the randomized timing groups over this interval. It does not describe how every participant changed: individuals may have had changes of different sizes or directions.

Patient activation is relevant to the program's stated aims because the intervention sought to increase engagement and support navigation of mental health services. The endpoint therefore captures a patient-reported construct related to those aims. It is not itself a direct measure of service use, communication quality, or clinical status. The registry does not report a threshold for a clinically important PAM-MH change, so the size of a numerical difference cannot by itself establish whether participants would regard that difference as meaningful.

7. Results Posted in the Registry

• Active PARTNER-MH: mean 5.70 versus 9.10 on control; difference -3.40 (95% CI -12.74 to 5.94), standardized effect d = -0.24; z-test p = 0.476.

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.

Perceived Efficacy in Patient-Physician Interactions Scale (PEPPI-5) Change

• 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:
  • Active PARTNER-MH: mean 6.50 versus 1.20 on control; difference 5.30 (95% CI -1.80 to 12.40), standardized effect d = 0.49; z-test p = 0.144.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Active PARTNER-MH and the control. The interval gives the range of effects that remain compatible with the data.

UCLA Loneliness Scale (ULS-6) Change

• 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:
  • Active PARTNER-MH: mean -0.60 versus -0.30 on control; difference -0.30 (95% CI -2.91 to 2.31), standardized effect d = -0.07; z-test p = 0.822.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Active PARTNER-MH and the control. The interval gives the range of effects that remain compatible with the data.

Patient Health Questionnaire (PHQ-9) Change

• 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:
  • Active PARTNER-MH: mean -3.60 versus 0.10 on control; difference -3.70 (95% CI -7.62 to 0.22), standardized effect d = -0.62; z-test p = 0.064.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Active PARTNER-MH and the control. The interval gives the range of effects that remain compatible with the data.

The posted numerical secondary comparisons cover patient-perceived efficacy in patient-physician interactions, loneliness, and depressive symptoms. Across these outcomes, the estimated between-group differences point in different directions rather than forming a uniform pattern. The confidence intervals for the posted comparisons include zero, so the results do not establish clear separation between the randomized groups on these measures.

The registry also lists the Veteran's RAND 12-item Health Survey and the Working Alliance Inventory Short-Revised as secondary outcomes, but their numerical results are not reported in the registry record. As a result, the posted secondary summaries offer only a partial view of the full set of outcomes named in the record.

These measures address related but distinct aspects of health, communication, relationships, and symptoms. They are not interchangeable with the primary PAM-MH activation measure. Their pattern does not overturn or confirm the primary result; rather, it provides additional, uncertain outcome information alongside the primary comparison. The registry does not report a prespecified hierarchy for interpreting secondary outcomes or an analysis plan addressing their joint interpretation.

Unadjusted secondary comparisons carry less weight when several outcomes are examined because the chance of at least one apparently unusual result can increase as more comparisons are considered. General statistical explanation: multiplicity procedures can control a chosen error rate across a family of tests, but they can also affect precision and the interpretation of individual results. Whether such procedures were planned or applied is not reported in the registry record. Secondary results are best viewed as exploratory signals, not as stand-alone confirmation of an intervention effect.

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

• Veteran's RAND 12-item Health Survey (VR-12) Change
• Perceived Efficacy in Patient-Physician Interactions Scale (PEPPI-5) Change
• Working Alliance Inventory Short-Revised (WAI-SR) Change
• UCLA Loneliness Scale (ULS-6) Change
• Patient Health Questionnaire (PHQ-9) Change

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean change represent?

For a continuous outcome, a group mean summarizes the average recorded value across the participants included in that group. For a change outcome, each value represents movement from baseline to a later assessment, and the group mean is the average of those changes. The standard deviation describes how spread out individual change values are around their group mean. It is not the same as the uncertainty in the group mean or the uncertainty in a between-group comparison.

The primary result reports mean changes of 5.7 and 9.1, with standard deviations of 16.5 and 11.7, respectively. The estimated mean difference is -3.4 for active PARTNER-MH relative to waitlist control. That contrast is calculated from the posted summaries without adjustment. It summarizes the difference in average change, not a difference experienced by every participant.

How should the confidence interval be read?

A confidence interval describes uncertainty around an estimate under the statistical procedure used to construct it. In general, a wider interval indicates less precision than a narrower interval. The primary interval, from -12.74 to 5.944, crosses zero. Zero represents no difference in mean change between the groups on the scale used for this contrast. Because the interval includes values on either side of zero, it is compatible with differences favoring either group, as well as little or no difference.

A confidence interval does not give the probability that the true effect is inside this particular interval, and it does not resolve whether a difference is important to participants. The registry does not report a clinically meaningful threshold for PAM-MH change. Interpretation therefore needs to consider both the interval's width and the absence of a reported importance threshold, rather than relying on the point estimate alone.

What does the unadjusted p-value say?

The unadjusted p-value for the primary comparison is 0.476. In general, a p-value describes how compatible the observed data are with a specified null model, assuming the model's conditions hold. It is not the probability that the null hypothesis is true, nor is it a measure of the size or importance of a difference. Here it should be considered alongside the estimated difference and its confidence interval. The registry record does not report a prespecified primary analysis or the assumptions used for a sponsor analysis.

The comparisons displayed in the posted results are straightforward calculations from summary statistics. They are not reported as adjusted model estimates. The record lists no reported analyses, so the formal analysis approach, any covariate adjustment, and any handling of the crossover structure are not reported in the registry record.

Why can spread matter?

General statistical explanation: when participant-level outcomes vary widely within groups, a group mean can be estimated less precisely unless there is enough information to offset that variability. The PAM-MH change standard deviations indicate that individual changes were dispersed around their group means. Over-dispersion is especially relevant when a model assumes variability is lower or more uniform than it actually is; such a mismatch can make uncertainty estimates unreliable. These results are continuous outcomes summarized by means and standard deviations, and the registry does not report a separate over-dispersion assessment or model.

More generally, the standard deviation and standard error answer different questions. A standard deviation describes participant-to-participant spread. A standard error describes uncertainty in an estimate, such as a mean or mean difference, under a statistical model. The registry summaries include standard deviations and comparisons, but do not describe a complete model-based analysis or its diagnostics.

What does the design imply for analysis?

General statistical explanation: a crossover design can involve measurements under more than one treatment condition for the same participant, so the relationship between repeated measurements may matter to analysis. The registry describes randomized timing, immediate intervention for one group, and a waitlist period for the other. It does not report whether the primary comparison used repeated measurements, paired information, period effects, or a crossover-specific model. The posted mean-difference calculation should therefore be read as an unadjusted comparison of the reported group summaries, not as evidence that those design features were modeled.

The registry record also does not report the allocation concealment process, the statistical analysis plan, missing-data methods, the analysis population, or interim analyses. No assumptions about these elements can be inferred from the reported summary statistics.

11. Confidence Intervals and Precision

The primary mean difference is -3.4, with a reported 95% confidence interval from -12.74 to 5.944. The interval includes zero and covers differences in both directions. It therefore does not pin down the direction or size of the between-group difference with high precision. The endpoint group standard deviations, 16.5 and 11.7, also show that participant changes varied around their respective group means.

Precision is distinct from whether an estimate is statistically distinguishable from zero. The confidence interval communicates a range of values compatible with the data and the interval procedure; the point estimate is only its center. The unadjusted p-value is 0.476, but that value does not show that the groups are equivalent. Establishing equivalence would require an appropriate design and a prespecified margin, neither of which is reported in the registry record.

The registry does not report a clinically important difference for PAM-MH, so the interval cannot be classified against a participant-centered threshold. The reported outcome summaries include 18 participants per arm, while enrollment is recorded as 50. The registry does not explain the relationship between these counts, the number with observed 6-month scores, or whether missing outcomes affected the estimate. This limits assessment of the precision and potential representativeness of the comparison. The interval also does not account for any analysis choices or multiplicity adjustments that are not reported in the registry record.

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 events. They are illustrations based on the observed effect, rather than the trial's original sample-size justification. The assumptions listed for this illustration are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect. The registry's own original design assumptions are not reported in the registry record.

The 80% power column gives the estimated participants per arm for a future study to have an 80% chance of detecting the specified effect under the stated assumptions, if that effect and the assumptions are correct. The 90% power column makes the corresponding estimate for a 90% chance. These are planning quantities, not guarantees. They do not indicate how likely the current trial was to find an effect, and they do not say whether the observed result is true.

Each planning row uses a different fraction of the observed effect: the full observed effect, 75% of it, or 50% of it. Smaller effects are harder to distinguish from random variation under the same design assumptions, so they require more participants per arm to reach the same target power. The planning estimates should be interpreted cautiously because the observed effect comes from a pilot comparison and may not be a stable estimate for future planning.

These figures are not observed power. They describe hypothetical future-study requirements under the stated assumptions; they do not replace interpretation of the current estimate, confidence interval, and the uncertainty in the posted results.

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 = -3.400; pooled standard deviation σ = 14.303.
2. n = 2 × (1.96 + 0.842)² × 14.303² / -3.400² = 277.8, rounded up to 278 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 <- -3.4                      # observed difference in means
sigma <- 14.3027969292723                     # 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(4515771)
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 = 278 (80% power), 372 (90% power)
 75% of observed effect: n per arm = 494 (80% power), 662 (90% power)
 50% of observed effect: n per arm = 1,112 (80% power), 1,488 (90% power)
power.t.test: 278.8 
Simulated power at n = 278 per arm: 0.797 (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 identifies a primary PAM-MH outcome and lists several secondary outcomes. It does not report a statistical analysis plan describing how outcomes were prioritized, how many formal hypotheses were tested, or whether any adjustment for multiple comparisons was planned. The posted secondary comparisons are unadjusted. Without a documented multiplicity strategy, individual secondary p-values should not be treated as if they were the sole test in a prespecified analysis.

The registry record does not report methods for missing data, such as imputation, likelihood-based analysis, or sensitivity analyses. It also does not state whether the primary analysis used an intention-to-treat population, a per-protocol population, or another defined analysis set. The primary outcome summaries report 18 participants in each arm, but the record does not explain the gap between these counts and the enrollment of 50 or identify the reasons for unavailable outcome data. The extent and pattern of missingness, and its possible influence on the estimated comparison, are therefore not reported in the registry record.

The randomized timing design is described as crossover, but the registry record does not report a model accounting for repeated measurements, periods, sequence, or other crossover-related features. It also does not report interim analyses, covariate adjustments, model diagnostics, or the sponsor's detailed analysis. These omissions do not establish that such procedures were absent; they mean that their use and results are not reported in the registry record. The unadjusted summary-based comparisons should be distinguished from a fully specified analysis of the trial.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety summaries report no serious adverse events in either group: the serious-event count is 0 in the active PARTNER-MH group and 0 in the waitlist control group. The associated at-risk figures are 30 and 20, respectively. Deaths are reported as 0 in both groups.

For other adverse events, the record reports 1 in the active PARTNER-MH group and 0 in the waitlist control group, with at-risk figures of 30 and 20. No serious adverse-event terms are listed. The registry does not describe the nature of the other reported event, its timing, or whether it was considered related to the intervention.

These counts are descriptive safety information, not proof that adverse events cannot occur. The registry record does not provide a detailed adverse-event collection method or explain the relationship between the safety at-risk figures and the primary outcome summaries. The figures should be read as the events recorded in the registry, not as a complete assessment of safety beyond the study.

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

The primary result is an uncertain estimate of the difference in mean PAM-MH change between participants assigned to immediate PARTNER-MH and those assigned to the waitlist period. The point estimate favors greater mean change in the waitlist control group, but the confidence interval includes differences in either direction. The posted summary therefore does not establish a clear difference in activation change between the groups at 6 months.

This is not evidence that the groups were equivalent, nor does it prove that there was no effect. A broad interval can include both modest and larger differences. The record does not state what change participants would consider important, so the practical importance of values within the interval cannot be determined from these results alone.

The findings address one patient-reported outcome over one specified period. The program's aims also included service navigation, engagement, and communication, while the study collected other questionnaires and some interviews. A change in PAM-MH does not directly establish a change in each of those other domains. Nor do the posted summary statistics describe individual experiences or explain how participants viewed the program.

The randomized waitlist arrangement helps define a comparison of intervention timing, but details of the primary analysis and missing data are not reported. The available result should therefore be understood as a summary of the reported outcome data, not as a complete causal account or a prediction of what would occur in other settings. The registry record does not establish longer-term effects, effects after the waitlist group received the intervention, or generalizability beyond the described population and VA mental health setting.

17. Why This Trial Matters Statistically

This trial is statistically informative because it separates a plausible intervention question from the uncertainty in its estimate. PARTNER-MH was designed to support navigation, engagement, and patient-provider communication through trained peer navigators. The primary outcome, patient activation, relates to those aims, but the observed group comparison is imprecise and does not establish a clear difference at 6 months.

The record illustrates why an estimate should be read together with its confidence interval. A single point estimate can suggest a direction, but the interval shows how much uncertainty remains. Here, the interval crosses zero and includes a range of effects in both directions. The unadjusted p-value does not resolve that uncertainty or show whether a difference would matter to participants.

The distinction between a pilot result and a definitive evaluation also matters. Planning figures based on the observed effect can illustrate the scale of a future study under stated assumptions, but they are sensitive to the effect used and do not establish the best design. The registry's original sample-size justification and formal statistical plan are not reported, limiting the ability to judge the trial's intended precision.

Finally, reporting details shape interpretation. The record supplies group summaries and secondary outcomes but does not report missing-data procedures, analysis populations, multiplicity handling, or a detailed crossover analysis. These are not merely technical details: they affect how readers judge uncertainty and the scope of conclusions. Transparent reporting of those methods would help readers distinguish the reported descriptive comparisons from a full trial analysis.

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.

The primary outcome summaries include 18 participants in each arm, while the registry records enrollment of 50. The registry does not explain this difference or report how many participants completed each assessment. Missing-data methods and reasons for missing outcomes are not reported, so the potential effect of incomplete follow-up cannot be assessed.

The record labels the study crossover and describes randomization to immediate or delayed intervention, but it does not explain the analysis of the timing design. It does not report whether repeated observations, treatment periods, or other features of crossover designs were accounted for in the primary comparison. The displayed comparison is an unadjusted calculation from posted summary statistics.

Although the registry names five secondary outcomes, numerical results are not reported for all of them. It does not report how secondary outcomes were prioritized or whether any multiplicity adjustment was used. Several methodological details are also not reported, including the primary analysis population, covariate adjustment, missing-data approach, and the original sample-size justification. The posted planning figures are based on the observed effect and are not evidence of the original design rationale.

The registry describes a pilot study and a specific population receiving outpatient VA mental health services. The record does not establish whether findings would extend to other populations or service settings. It also does not report a clinically important threshold for the primary measure or longer-term results after the 6-month assessment. These limits constrain interpretation of practical importance, durability, and generalizability.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Improving Patient-Provider Communication to Reduce Mental Health Disparities — NCT04515771.
• Registry record last updated 2024-09-19; status last verified 2024-08.
• Results first posted 2024-09-19.
• 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

NCT04515771 is a completed randomized, unmasked crossover study of PARTNER-MH, a peer-navigator behavioral intervention for racially and ethnically minoritized Veterans receiving outpatient VA mental health services. Participants were assigned to immediate intervention or a waitlist arrangement, with usual mental health services available in both groups. The registry records enrollment of 50 and identifies the VA Office of Research and Development as sponsor.

The primary outcome was change in PAM-MH from baseline to 6 months. Mean change was 5.7 for active PARTNER-MH and 9.1 for waitlist control; the unadjusted mean difference was -3.4, with a 95% confidence interval from -12.74 to 5.944 and an unadjusted p-value of 0.476. The interval includes differences in either direction and does not establish a clear group difference.

Secondary outcomes show varied estimates, and not all outcomes named in the registry have numerical results reported. The registry does not report detailed analysis methods, missing-data procedures, or multiplicity handling. Safety summaries record no serious adverse events and no deaths in either group.