Safety and Tolerability After Four Weeks of Treatment With AZD1656 in Patients With Type 2 Diabetes: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Tolerability After Four Weeks of Treatment With AZD1656 in Patients With Type 2 Diabetes (NCT00856908), a randomized phase 2 study. The primary outcome is Systolic Blood Pressure, Change From Baseline to End of Treatment.

2. Clinical Question

3. Trial Design

This was a randomized, single-blind, placebo-controlled, parallel-group Phase IIa study. Its stated focus was the safety and tolerability of multiple oral doses of AZD1656 over four weeks in patients with type 2 diabetes treated with insulin. The registry lists an enrollment of 20. The meaning of that enrollment figure in relation to the participants included in each posted outcome is not explained in the registry record.

The intervention descriptions state that participants underwent dose titration during 4 days to a tolerable dose taken twice daily, then continued at that dose twice daily for another 24 days. The registry does not report the dose levels, how tolerability was defined, or whether the titration schedules differed between groups. Although the study is described as single-blind, which parties were masked is not reported in the registry record.

The primary outcome was systolic blood pressure change from baseline to the end of treatment. Baseline is defined as pre-dose on the first day of dosing, and the end-of-treatment measurement as the morning following the treatment period. The primary outcome is reported as a mean with standard deviation. The registry also lists pharmacokinetic outcomes for AZD1656 and changes in glucose, insulin and C-peptide measures as secondary outcomes.

The outcome-level results list 14 participants in the experimental group and 5 in the placebo group. The registry record does not explain why those outcome counts differ from the enrollment figure, or whether the difference reflects exclusions, missing measurements, or another analysis-population definition. Additional information about eligibility criteria, recruitment, allocation procedures, study sites, and the masking process is not reported in the registry record.

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.

6. Primary Endpoint

The registry lists the primary outcome as Systolic Blood Pressure, Change From Baseline to End of Treatment, measured over Baseline is pre-dose first day of dosing, end of treatment is the morning following the treatment period.

The primary endpoint is the change in systolic blood pressure from baseline to the end of treatment, measured in mmHg. It is a continuous outcome: each participant contributes a numerical measurement, and the arm summaries describe the average change and its variability. The specified baseline is pre-dose on the first day of dosing; the end-of-treatment measurement is taken the morning following the treatment period.

Blood pressure is a physiological measure that can be recorded numerically, making it possible to summarize the average change within each randomized group. In general, a change-from-baseline endpoint describes how measurements at the end of treatment differ from the defined starting point for participants with recorded measurements. It does not, by itself, establish that a difference between groups is caused by treatment. For that interpretation, an appropriate between-group analysis and information about its uncertainty are needed.

The registry lists the outcome parameter as a mean and its dispersion as a standard deviation. A standard deviation describes how spread out individual observations are around the group mean; it is not the same as a confidence interval for the mean or for a treatment contrast. The registry does not report a clinically important threshold for systolic blood pressure change, an endpoint measurement schedule beyond the stated time points, or an inferential analysis of the between-group contrast. The posted outcome therefore supports a descriptive reading of the group summaries, not a conclusion about the precision or statistical significance of a treatment effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous and is reported using a mean and standard deviation for each group. In general, a mean gives the arithmetic average of the recorded observations, while a standard deviation describes their spread around that average. The standard deviation is a feature of the observations; it does not directly give the uncertainty of the mean or of a comparison between randomized groups.

What would a between-group estimate represent?

In general, a treatment comparison for a continuous endpoint estimates how the outcome differs between groups. For a change-from-baseline outcome, the comparison concerns the groups' changes over the specified period, not simply the end-of-treatment measurements considered without their baselines. A confidence interval around the comparison would express the range of values compatible with the data and the statistical model at the chosen confidence level. The registry record does not report such an estimate or interval for systolic blood pressure.

The record's outcome summaries are not a substitute for that comparison. A reader cannot determine the precision of the treatment contrast from group means and standard deviations alone without choosing and applying an analysis method and making assumptions. The registry marks the two-arm continuous comparison as missing or not estimable. No inferential result should be attributed to the sponsor on the basis of the posted arm summaries.

Why does dispersion matter?

In general, greater variability among observations makes a group mean less precise when the number of observations is held constant. With limited outcome counts, estimates can be sensitive to individual observations, and the data may provide limited information about the range of plausible group differences. The standard deviations of 8.5 in the experimental group and 6.4 in the placebo group describe observed spread; they are not confidence limits and should not be read as such.

Methods based on a normal approximation often rely on assumptions about the distribution of the outcome or of the estimator. If the data are markedly skewed or contain influential observations, a simple mean-based model may not describe uncertainty well. The registry record does not report participant-level distributions, diagnostic checks, transformations, robust methods, or an alternative model. It is therefore not possible to assess those assumptions from the posted summaries.

What does randomization contribute?

In general, random assignment is intended to make treatment groups comparable on average at the start of a trial, including with respect to characteristics that are not measured. It does not guarantee that the realized groups are balanced, particularly when outcome counts are limited. Randomization also does not resolve issues arising after assignment, such as missing outcome measurements, non-adherence, or departures from the planned analysis. The registry record does not describe the allocation sequence, concealment procedures, or analysis population for the primary outcome.

The study is listed as single-blind, but which people were masked is not reported in the registry record. Masking can reduce some forms of expectation-related influence on treatment delivery or measurement, depending on who is masked and how the outcome is collected. The available description is insufficient to assess those details.

How should planning illustrations be understood?

In general, a sample-size calculation asks how many participants per arm would be needed under specified assumptions to detect a chosen effect with a chosen probability of rejecting a null hypothesis when that effect is present. The registry's planning description uses a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect defined as a stated fraction of the observed effect. These are planning assumptions, not results from the randomized comparison.

Such calculations depend on the effect size and variability used, the desired power, allocation, outcome model, and significance level. A calculation based on an observed effect is only an illustration: the observed estimate may be imprecise and may not represent the effect that a future study should target. A planning number is not observed power, and it does not change the evidence available from the current trial. The registry record does not report the trial's own sample-size justification, so these planning assumptions should not be taken as its design rationale.

Multiplicity also matters when several outcomes or comparisons are considered. In general, testing many hypotheses without an appropriate strategy can increase the chance of at least one chance finding. The registry lists a primary outcome and multiple secondary outcomes, but does not report a multiplicity adjustment or a hierarchy of tests. No inferential analyses are posted, so there are no reported outcome-specific p-values to interpret or combine.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Experimental", "Placebo Comparator")
n   <- c(14, 5)
m   <- c(0.4, 5)
sp  <- c(8.5, 6.4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Experimental  14  0.400  8.500  -4.508  5.308
CARM  Placebo Comparator  5  5.000  6.400  -2.947  12.947

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome, systolic blood pressure change from baseline to the end of treatment, and eight posted secondary outcomes. The secondary outcomes include pharmacokinetic measures of AZD1656 and changes in glucose, insulin, and C-peptide measures. The record lists 13 outcome measures in total, but gives no inferential analyses; the number of posted analyses is zero.

When a study assesses multiple outcomes, multiplicity can affect how strongly individual statistical findings should be interpreted. In general, a prespecified hierarchy or adjustment can help address the increased chance of false-positive findings across multiple tests. Whether such a strategy was planned or used is not reported in the registry record. Since no analyses are posted, the record does not support interpretation of a set of inferential findings or assessment of any adjustment.

The outcome-level results give 14 participants for the experimental primary-outcome summary and 5 for the placebo summary. The registry does not report a participant flow, reasons for missing measurements, imputation, sensitivity analyses, or a definition of the analysis population. It also does not state whether the primary outcome analysis followed randomized assignment or used another population. These omissions limit assessment of possible bias from missing outcome data and of how the posted summaries relate to the enrolled participants.

The registry record does not report an interim-analysis plan or stopping rules. It also does not report a statistical analysis plan. In general, those details can clarify which analyses were prespecified and how decisions about outcomes, missing data, and multiplicity were handled. Their absence from the record should be treated as missing information, not as evidence that a particular method was or was not used.

12. Safety Results

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

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry reports serious adverse events for the experimental group among 15 participants at risk and for the placebo group among 5 participants at risk. The reported count of participants affected by a serious adverse event is 0 in each group. The registry does not list any top serious adverse-event terms. Death counts are not reported in the registry record.

The record also reports other adverse events among 15 participants at risk in the experimental group, with 13 affected, and among 5 participants at risk in the placebo group, with 3 affected. These are counts, not estimates of a comparative safety effect. The registry entry does not provide event-level descriptions or explain whether participants could contribute more than one event to the other-adverse-event figures.

In general, a zero count of reported serious adverse events does not establish that the risk is absent. Safety interpretation depends on the duration of observation, the number of participants observed, event definitions, completeness of reporting, and the distinction between participants affected and events recorded. The registry does not provide enough detail to assess all of these features or to compare safety statistically. The at-risk counts for these safety outcomes also differ from the primary-outcome counts, and the reason is not reported in the registry record.

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

The posted primary-outcome results describe mean changes in systolic blood pressure in the experimental and placebo groups, along with standard deviations. They do not report a formal estimate of the difference between groups or the uncertainty around that estimate. A descriptive contrast between group summaries is not equivalent to a prespecified inferential analysis, and no new contrast is calculated.

These results therefore cannot establish whether the observed group summaries reflect a precise difference, a chance fluctuation, or other features of the data. The registry does not report a confidence interval, p-value, adjusted analysis, or individual measurements. It also does not report a clinically important threshold that would help judge the practical importance of a blood pressure change. The missing comparison is not evidence that there was no difference, and it does not establish equivalence.

The study was described as a safety and tolerability assessment of multiple oral doses of AZD1656 over four weeks in insulin-treated patients with type 2 diabetes. The posted adverse-event counts give a limited account of events recorded during the study, but the registry does not provide detail sufficient to assess event types, timing, recurrence, or comparative risks. Zero reported serious adverse events in the listed groups should be read as a count in this record, not as proof that serious events cannot occur.

The results also should not be generalized beyond the recorded study population without additional evidence. Detailed participant characteristics, eligibility criteria, dose levels, and the reasons for the outcome counts are not reported in the registry record. The registry record supports a narrow descriptive account of the outcomes it posts; it does not provide enough inferential or methodological information for a firm conclusion about the treatment effect, the precision of that effect, or broader safety.

14. Why This Trial Matters Statistically

This trial is statistically notable because it reports arm-level summaries for a continuous primary outcome but no inferential comparison. That distinction is important in clinical research: group means describe the observed data, whereas a treatment-effect estimate and its uncertainty address how well the data distinguish a group difference from sampling variation. The registry record does not include the latter for systolic blood pressure.

The study also has different participant counts for its primary outcome summaries and safety outcomes. Those figures serve different purposes and should not be conflated. Without a participant flow or analysis-population description, readers cannot determine why the outcome counts differ from enrollment or from the safety at-risk counts. Reporting those reasons would help readers judge completeness and potential missing-data bias.

Safety reporting highlights another statistical distinction: a zero count of serious adverse events is an observation over a limited study, not a precise estimate of rare-event risk. Conversely, the other-adverse-event counts are not by themselves a comparative analysis. Both types of result need clear definitions, observation windows, and an explanation of who contributed to each denominator.

Finally, this record illustrates why planning calculations and trial findings must be kept separate. The stated planning approach describes assumptions for illustrative sample-size calculations; it is not evidence of the trial's statistical power or its original design justification. The record does not report a sample-size rationale or inferential analyses. Clear separation of design assumptions, observed summaries, and statistical conclusions is essential for accurate interpretation.

15. 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 registry record does not report a statistical analysis plan, a sample-size justification, or inferential results for the primary outcome. It marks the two-arm continuous comparison as missing or not estimable, so the posted means and standard deviations cannot be accompanied by a sponsor-reported treatment contrast or interval describing its precision.

Outcome counts are not fully explained. The registry lists an enrollment of 20, while the primary-outcome results include 14 participants in the experimental group and 5 in the placebo group. Safety outcomes use at-risk counts of 15 and 5. The record does not describe participant flow, reasons for missing outcome data, exclusions, or the populations used for these summaries. No imputation or sensitivity analysis is reported.

The study description gives a four-week treatment period and a titration schedule, but the actual dose levels and details of tolerability-based titration are not reported. The registry identifies the study as single-blind without stating who was masked. It also does not report the allocation procedure, detailed eligibility criteria, baseline participant characteristics, or clinical importance criteria for the primary outcome.

Safety data are limited to the posted counts. The registry does not report death counts, top serious adverse-event terms, event-level detail for other adverse events, or additional information needed to evaluate duration and completeness of safety observation. The absence of these details limits interpretation of both the safety profile and differences between the listed groups.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety and Tolerability After Four Weeks of Treatment With AZD1656 in Patients With Type 2 Diabetes — NCT00856908.
• Registry record last updated 2012-12-06; status last verified 2012-11.
• Results first posted 2012-11-26.
• 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.

19. Record Summary

The registry describes a randomized, single-blind, placebo-controlled, parallel-group Phase IIa study of oral AZD1656 in patients with type 2 diabetes treated with insulin. The stated treatment period was four weeks, with titration during 4 days followed by treatment at a tolerable dose twice daily for another 24 days.

The primary outcome was mean change in systolic blood pressure from baseline to the morning following the treatment period. Posted summaries report a mean change of 0.4 mmHg with standard deviation 8.5 for 14 experimental-group participants, and 5.0 mmHg with standard deviation 6.4 for 5 placebo participants. The registry does not report an inferential comparison for this outcome.

Serious adverse-event counts were 0 among 15 experimental participants at risk and 0 among 5 placebo participants at risk. Other adverse events affected 13 of 15 experimental participants and 3 of 5 placebo participants. The registry record does not explain the differing outcome counts or provide a statistical analysis plan.