User Study of an Investigational Blood Glucose Monitoring System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for User Study of an Investigational Blood Glucose Monitoring System (NCT01447121), a na na study. The primary outcome is Number of Self-Test Fingerstick Blood Glucose (BG) Results Within +/- 15mg/dL (<75 mg/dL) or Within +/- 20% (>=75 mg/dL) of Laboratory Glucose Method.

2. Clinical Question

3. Trial Design

This was a completed, single-group device evaluation listed under the title “User Study of an Investigational Blood Glucose Monitoring System,” with the official title “Tatsu/Tradewind System User Performance Evaluation.” The registry lists the phase as NA, allocation as NA, and masking as NONE. Its design description identifies intended users testing the investigational system rather than separate treatment and control arms. The record lists enrollment as 118 and the sponsor as Ascensia Diabetes Care.

The study start and primary completion are both recorded as 2011-09, and the status is COMPLETED. The intervention is the Tatsu/Tradewind Investigational BG Monitoring System, classified as a device. Untrained subjects with diabetes used the system to self-test capillary blood obtained by fingerstick. Their meter results were compared with results from a laboratory glucose method. The registry describes the reference as capillary plasma glucose measured with a YSI Analyzer.

This design can assess how the device readings compare with a reference method under the described user-testing conditions. It is not a randomized controlled design: there is no allocated comparison arm or masked assignment in the record. Consequently, the design does not support interpreting differences between treatment groups or attributing a clinical outcome to the device. The registry does not report further details about the protocol, recruitment, the distribution of strip lots among users, or the procedures used to train or prepare participants beyond identifying them as untrained intended users.

The record says that 118 subjects tested one of 3 test strip lots, that results from 2 subjects were excluded from all data analyses, and that one subject’s test exceeded the protocol-defined interval between meter testing and reference testing. It describes 115(115x1)test results as possible. The exact analysis set and the relationship between these notes are not further explained 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

Analysis population for the primary outcome, as defined in the registry: 115(115x1)test results are possible. 118 subjects tested one of 3 test strip lots on the BGM system. Study results from 2 subjects were excluded from all data analyses as already described. One subject test exceeded time interval (defined in protocol) between meter test and reference method.

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 Number of Self-Test Fingerstick Blood Glucose (BG) Results Within +/- 15mg/dL (<75 mg/dL) or Within +/- 20% (>=75 mg/dL) of Laboratory Glucose Method, measured over 1 hour.

The primary endpoint is a count: the number of self-test fingerstick blood glucose results that meet the registry’s agreement criterion relative to laboratory glucose results. The criterion varies according to the reference value. For reference results <75mg/dL, a meter result is within +/- 15mg/dL if its difference from the reference falls inside that absolute margin. For reference results >=75mg/dL, the criterion is a difference within +/- 20% of the reference. These are the thresholds as recorded in the endpoint description.

The reference method is the YSI Analyzer applied to capillary plasma glucose. Comparing a meter result with a laboratory reference is useful for describing measurement agreement: it addresses how close readings are to the specified reference under the study conditions. It does not, by itself, measure a health outcome or establish how readings affect decisions or outcomes in ordinary use.

The outcome unit is BG test results, and the timeframe is 1 hour. The registry describes the possible number of results as 115(115x1)test results. However, the observed number meeting the criterion, the number failing it, and any uncertainty interval around the count are not reported in the registry record. Without those results, the endpoint definition can be explained, but the degree of observed agreement cannot be quantified.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main statistical feature of this evaluation is that it defines a count endpoint based on paired measurement agreement. Each eligible self-test reading is assessed against a laboratory reference result, and the endpoint counts readings that satisfy the specified tolerance. The registry describes the measurement method and the rule for classifying a reading, but it does not report an analysis estimate or the count itself.

What does the count represent?

A count reports how many observations meet a defined condition. In this study, the condition is agreement with the reference method within the stated glucose-dependent limits. The outcome unit is BG test results, not a direct measure of a participant’s health status. The record says 115(115x1)test results were possible. It also describes exclusions and a timing issue, but does not provide a complete account of the analysis set or a final count of qualifying results.

Counts can be useful when the question is whether observations satisfy a practical criterion. They are less informative about the size and pattern of measurement differences than a full distribution of paired differences. For example, the count alone would not distinguish results close to the reference from results near the edge of an allowed margin. This is a general statistical point; the registry does not report additional summaries that would address those features.

Why compare with a reference method?

A reference method gives a defined point of comparison for assessing measurement agreement. Here, meter readings were compared with capillary plasma glucose measured using a YSI Analyzer. The comparison is within the same testing context, rather than a comparison of outcomes across assigned groups. General statistical interpretation distinguishes agreement from association: two methods can track changes together while still differing in their readings. Agreement limits address the size of differences allowed for this endpoint, but the registry does not provide the observed differences or the number within the limits.

The endpoint applies an absolute tolerance when the reference result is <75mg/dL and a relative tolerance when it is >=75mg/dL. The threshold rule determines how each paired reading is classified. It does not describe how many readings fall into either reference range, and those counts are not reported in the registry record. The threshold categories should therefore not be mistaken for observed findings.

What would an uncertainty interval tell a reader?

In general, a confidence interval describes the range of estimates compatible with the observed data under a specified statistical method. It helps readers assess precision: a wider interval indicates less precision than a narrower one. A confidence interval is not reported for this primary endpoint in the registry record. Without the observed count and an interval, the precision of an agreement estimate cannot be evaluated from this record. No interval should be inferred from the enrollment or possible-result information alone.

Why can count data require care?

General methods for count outcomes may use distributional assumptions. Some count data are more variable than a simple model assumes, a feature called over-dispersion. When over-dispersion is present, methods that fail to account for it can understate uncertainty. Whether over-dispersion is relevant depends on how the observations arise and how the analysis is specified. The registry does not report a statistical model, a dispersion estimate, or an analysis of over-dispersion for this endpoint. It would therefore be inappropriate to claim that a particular count model was used or that a specific distributional assumption was checked.

There is also a general issue of dependence when multiple observations come from the same person or testing context. Statistical methods may need to account for such clustering when observations are not independent. The record describes 115(115x1)test results as possible, but does not provide an analysis model or enough detail to assess the handling of dependence. No adjustment for clustering should be attributed to the study based on this record.

What does the record say about the analysis?

The registry lists 0 analyses. It does not report a sponsor analysis, an effect estimate, a confidence interval, a hypothesis test, or a statistical plan for the primary endpoint. The record also does not report whether analyses were prespecified, whether any interim analyses occurred, or how the study’s enrollment was justified. These details are not reported in the registry record, and the endpoint description cannot substitute for them.

The record includes a general planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not evidence that this single-group device evaluation used a two-arm design, and not a description of its observed analysis. Sample-size illustrations are planning aids, not observed power. The record does not report a trial-specific statistical plan that connects those assumptions to the registered design.

No numerical estimate should be reconstructed from the endpoint definition or study description. The registry’s reported information supports a description of the measurement question and its method, but not a quantitative conclusion about the primary or secondary outcome.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 0 analyses. The primary outcome is the number of self-test fingerstick blood glucose results within the specified limits of the YSI laboratory method. A secondary outcome concerns study staff results within the stated limits when testing subject blood glucose. The outcome descriptions define what is to be counted, but neither outcome’s result is reported in the registry record.

When a study examines more than one outcome, multiplicity can matter because repeated statistical testing may increase the chance of finding an apparently notable result by chance. This is a general statistical consideration, not a claim that a particular multiplicity problem occurred in this study. The record does not report a statistical analysis plan, a testing hierarchy, an adjustment for multiple comparisons, or whether any formal hypothesis tests were conducted. No approach to multiplicity can therefore be attributed to the study.

The registry says that results from 2 subjects were excluded from all data analyses and that one subject’s test exceeded the protocol-defined interval between meter testing and reference testing. It describes 115(115x1)test results as possible. Further details about missing readings, the reasons for the exclusions, the handling of the timing issue, or the final analysis population are not reported in the registry record. The record also does not describe imputation or other methods for handling missing data.

These omissions matter for interpretation because an agreement count depends on which paired measurements are included. The available notes identify exclusions but do not establish how the endpoint result would change under another analysis population or missing-data approach. No sensitivity analysis is reported in the registry record.

11. 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 4% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports no serious adverse events affecting participants in the “Intended Users of the System” group: 0 of 118 were recorded as affected, with 118 listed as at risk for serious adverse events. The deaths field is null, so death results are not reported in the registry record. No serious adverse event terms are listed among the top serious terms.

Separately, the record lists 5 affected participants among 118 at risk for other, non-serious adverse events. These are counts in the registry’s adverse-event summary; the record does not supply descriptions of those events, their severity beyond the serious/non-serious categorization, or their relationship to the device. The serious-event count and other-event count refer to different categories and should not be combined.

Zero recorded serious adverse events in this group is a descriptive finding for this study record. It does not establish that serious events cannot occur, and the registry does not report enough detail to assess event ascertainment or attribution. Safety interpretation should remain limited to the counts and categories recorded, rather than implying a broader conclusion about risk.

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

This record describes an evaluation of how readings from an investigational blood glucose monitoring system compared with a laboratory reference when untrained intended users tested fingerstick blood. The primary endpoint is clearly defined as a count of test results within specified limits. That definition explains the measurement question, but the registry does not report the count or any estimate of the observed agreement.

Accordingly, the record cannot support a conclusion that the system did or did not meet the specified agreement limits. It also cannot quantify the precision of any agreement estimate, because no estimate or confidence interval is reported. The absence of a posted result is not itself a favorable or unfavorable result.

The design is single-group and unmasked, with no randomized control comparison described. It therefore addresses a device-to-reference measurement question in the testing conditions recorded, rather than the comparative performance of different devices or strategies. It also does not answer whether use of the device changes treatment decisions, health outcomes, or quality of life; those outcomes are not described as the primary question.

The registry’s notes about exclusions and the timing interval are relevant to understanding which observations may have been eligible for analysis, but the final analysis population is not fully described. The primary and secondary results, statistical plan, and methods for missing data are also not reported in the registry record. These gaps prevent a fuller assessment of the strength, precision, and robustness of the statistical evidence.

The safety record lists 0 serious adverse events among 118 at risk and 5 other adverse events among 118 at risk. Those counts are descriptive and do not establish causality or rule out unrecorded risks. Overall, the registry provides useful information about the design and endpoint definition, while leaving the central performance result and several interpretive details unavailable.

13. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the distinction between defining a measurement-performance question and reporting evidence that answers it. The endpoint sets explicit limits for comparing meter readings with a laboratory reference. Such limits make the intended classification rule understandable, but they do not reveal how many results met it or how precisely performance was estimated. Without the observed result, readers cannot evaluate the magnitude or uncertainty of agreement from the registry record.

The design also focuses attention on the appropriate scope of inference. A single-group study can describe readings in the tested setting and compare them with a reference method. It does not provide a randomized comparison between devices or strategies. Recognizing that distinction helps prevent a measurement-agreement endpoint from being interpreted as evidence about clinical outcomes or comparative effectiveness.

The registry records exclusions and a timing issue, while offering only limited information about the final analysis population. For a paired measurement endpoint, the availability and eligibility of both meter and reference readings are central to analysis. Clear reporting of exclusions, missing observations, and analysis methods allows readers to judge whether the estimate represents the intended testing population. Those details are not fully available in this record.

Finally, the registry lists outcome measures but no analyses. This makes the entry informative about the question the study set out to address, while limiting its value for assessing statistical results. The case underscores why outcome definitions, analysis populations, estimates, uncertainty intervals, and analysis plans each contribute different information. A clearly specified endpoint is an important starting point, not a substitute for reported results.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation for interpreting the statistical findings is that the registry record does not report the primary endpoint result. It gives the count definition and the comparison method, but not the observed number of qualifying readings, a proportion, an uncertainty interval, or a hypothesis test. The secondary outcome result is also not reported, and the record lists 0 analyses.

The description of the analysis population is incomplete. The record says results from 2 subjects were excluded from all data analyses, identifies one subject whose test exceeded a protocol-defined interval, and states that 115(115x1)test results were possible. It does not explain the final analysis set in greater detail, how the timing issue was handled, or whether other readings were missing or excluded.

The statistical plan is not reported in the registry record. There is no description of the model, variance assumptions, uncertainty estimation, prespecified testing strategy, multiplicity handling, or missing-data method. The record also does not report how enrollment was justified. Without those details and the outcome estimates, readers cannot assess the analysis choices or the precision and robustness of results.

The study is single-group and unmasked, with no randomized comparator arm. The findings, even if fully reported, would address agreement with the reference method under the described testing conditions rather than comparative or causal effects. The record also offers limited adverse-event detail: it lists event counts but does not describe the events or their relationship to the device. These limitations are specific to the information and design recorded for this evaluation.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: User Study of an Investigational Blood Glucose Monitoring System — NCT01447121.
• Registry record last updated 2016-02-29; status last verified 2016-01.
• Results first posted 2012-10-22.
• 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

NCT01447121 is a completed single-group evaluation of the Tatsu/Tradewind Investigational BG Monitoring System in untrained intended users with diabetes. The registry lists enrollment of 118, masking as NONE, and allocation as NA. Study start and primary completion are both recorded as 2011-09.

The primary endpoint counts self-test fingerstick glucose results within specified limits of a YSI laboratory glucose reference. The record describes possible results, exclusions, and a timing issue, but does not report the primary result, the secondary result, or any analysis. The statistical plan and final analysis population are not reported in the registry record.

The adverse-event summary records 0 serious adverse events among 118 at risk and 5 other adverse events among 118 at risk. The death result is not reported in the registry record. The entry therefore describes the study question and its measurement criteria, but does not provide the outcome estimates needed to quantify agreement.