User Performance Evaluation for DARIO™ BGMS: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for User Performance Evaluation for DARIO™ BGMS (NCT02357043), a na na study. The primary outcome is Accuracy - Blood Glucose Level Obtained by Layperson With the Dario Meter Compared to Blood Glucose Level on Yellow Springs Instrument Obtained by Nurse/Technician.

2. Clinical Question

This is a measurement-performance question, rather than a question about whether one treatment improves a health outcome relative to another. Interpreting it requires knowing what counts as an accurate reading, how the reference and device measurements are collected and matched, and how results are summarized across participants. Those details are not reported in the registry record. The summary also identifies usability as an aim, but it does not describe a separate usability outcome or report usability findings. Consequently, the recorded study objectives can be described, but the primary accuracy question cannot be answered from the registry results available.

3. Trial Design

The registry record identifies NCT02357043 as a completed study titled “User Performance Evaluation for DARIO™ BGMS.” The sponsor is LabStyle Innovations Ltd. The listed start is 2014-12 and primary completion is 2015-03. The condition is diabetes, and the enrollment is 368. The record classifies the design as single-group, with allocation listed as NA and masking listed as NONE. Phase is listed as NA.

The Dario Blood Glucose Monitoring System is the device participants were asked to use themselves according to its instructions. The study summary describes comparison with YSI, a reference measurement obtained by a nurse or technician. This measurement comparison does not turn YSI into a separately randomized treatment arm. The registry record explicitly notes that this is not a randomized comparison and that arms are not a like-for-like control comparison. The single-group classification and absent allocation are therefore important when interpreting the study: the described purpose is to evaluate device readings against a reference, not to estimate a randomized between-group treatment effect.

The registry record does not report recruitment procedures, eligibility criteria, study locations, participant characteristics, the detailed measurement protocol, or whether measurements were paired and analyzed at the participant level. It also does not describe any masking procedures beyond listing masking as NONE. The record lists two devices as interventions, but supplies an arm description only for the Dario system. Further details about the conduct of the YSI measurement are not reported in the registry record.

Although the study status is COMPLETED, completion status alone does not establish that results for every planned outcome were entered. The record lists one outcome measure and no analyses. It does not report a statistical analysis plan, sample-size justification for the actual study, or the results needed to judge accuracy. These omissions limit what can be inferred about the design and the findings, even though the study objective and broad measurement comparison are described.

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 Accuracy - Blood Glucose Level Obtained by Layperson With the Dario Meter Compared to Blood Glucose Level on Yellow Springs Instrument Obtained by Nurse/Technician, measured over 5 minutes.

The primary endpoint is titled “Accuracy - Blood Glucose Level Obtained by Layperson With the Dario Meter Compared to Blood Glucose Level on Yellow Springs Instrument Obtained by Nurse/Technician.” It concerns agreement between a layperson’s Dario meter reading and a nurse- or technician-obtained YSI reading. The stated timeframe is 5 minutes, and the unit is participants. The record characterizes the measure as a number of participants, but does not report the actual count or the rule used to classify a measurement as accurate.

In general, comparing a device measurement with a reference can help assess how closely the device readings correspond to the reference under the specified study conditions. Accuracy criteria matter because different allowable differences or classification rules can lead to different counts of readings considered acceptable. The registry record does not state an allowable error range, a threshold, or another decision rule, so the endpoint’s operational definition cannot be reconstructed from the record.

The endpoint is relevant to the stated device-evaluation objective because it directly compares the user-obtained reading with a reference reading. However, a description of what an endpoint is intended to measure is not itself evidence of performance. No observed accuracy count, estimate of agreement, uncertainty interval, or analysis result is reported in the registry record. Usability is mentioned in the study summary but is not described as the primary endpoint, and no separate usability result is reported.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General: measurement comparison. A device-agreement study asks how measurements from a device relate to measurements from a reference method. The reference is used as a comparator for measurement, rather than as a treatment assigned to a separate group. In this study description, the Dario reading is obtained by a layperson and the YSI reading by a nurse or technician. Interpreting the comparison depends on the measurement protocol, the timing and matching of readings, and the criterion defining acceptable accuracy. Those details are not reported in the registry record.

General: endpoint definition. An endpoint needs a precise operational definition before its count or estimate can be interpreted. For a participant-count outcome, the analysis must specify what qualifies a participant as meeting the endpoint, such as a prespecified agreement rule applied to their measurements. The record identifies the outcome as accuracy and gives its unit as participants, but does not state the classification rule or the number meeting it. Without those elements, a reader cannot tell what the recorded count would represent or compare it reliably with a different study.

General: paired measurements and dependence. When two methods are used to measure the same underlying quantity under a coordinated protocol, their readings may be naturally linked. Statistical methods should account for that relationship if the data are paired; treating linked observations as independent can misrepresent uncertainty. The registry description gives a comparison of Dario and YSI readings, but it does not report whether all readings were paired, how many measurement occasions were included, or how dependence was handled analytically. The actual analysis method is not reported in the registry record.

General: counts and denominators. A count of participants meeting an endpoint is easier to interpret when its denominator is clear. The denominator could depend on eligibility for the endpoint, availability of measurements, and the analysis population. Enrollment of 368 is reported, but the record does not state how many participants contributed to the primary endpoint or whether all enrolled participants had evaluable measurements. It would therefore be inappropriate to treat enrollment automatically as the endpoint denominator.

General: point estimates and uncertainty. A point estimate describes the result calculated from observed data. A confidence interval expresses uncertainty around an estimate under a stated statistical model and procedure; it is not a guarantee that the true value lies within the interval. In a device-comparison analysis, both the chosen summary and its interval matter. For example, a count, a proportion, or a measure of measurement agreement would answer different questions. The registry record does not report a primary estimate, confidence interval, or model, so no such quantity can be interpreted for this study.

General: hypothesis tests. A p-value, when used, measures how incompatible the observed data are with a specified null hypothesis under the assumptions of the test. It does not measure the probability that the null hypothesis is true, and it does not establish practical importance. A test also requires a stated hypothesis, analysis method, and data. The registry record lists no analyses and no primary result, so it does not support interpretation of a p-value or a claim of statistical significance.

General: variability and over-dispersion. Count data can vary more or less than a statistical model expects. Over-dispersion means observed variation exceeds the model’s assumed variation; if ignored, standard errors can be too small and confidence intervals too narrow. Whether this issue matters depends on the outcome structure and model. The registry record does not describe a count model, repeated-measure structure, or variance assessment, so there is no basis to say whether over-dispersion was relevant or addressed in the study’s analysis.

General: sample-size planning. Sample-size calculations are planning illustrations based on assumptions; they are not observed results and do not establish that a study had adequate precision. The planning assumptions recorded for this analysis specify a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. The record characterizes these as planning illustrations computed from an observed effect, not as the trial’s own design. No actual sample-size justification is reported in the registry record, and the primary observed effect is not reported there. Any planning value should therefore be read as a hypothetical illustration under its stated assumptions, not as observed power or evidence about the study’s findings.

The listed planning framework also assumes equal allocation between two arms, while the registered design is single-group and the comparison is described as device readings versus a reference instrument. This distinction matters: planning assumptions do not change the registered design or establish that the study enrolled randomized groups. No result from a planning exercise can substitute for a reported accuracy estimate and its uncertainty.

General: interpretation depends on the analysis plan. The analysis plan would ordinarily clarify the primary endpoint definition, analysis population, handling of incomplete measurements, and statistical method. It may also specify how secondary outcomes are handled and whether any subgroup analyses are planned. The registry record does not report these details. Since no analysis is listed, the methods actually used to produce a primary result cannot be assessed. A reader should distinguish the stated study aim from a completed statistical evaluation and should not infer an unreported method from the outcome title alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and no analyses. The primary outcome concerns accuracy of a layperson-obtained Dario reading compared with a nurse- or technician-obtained YSI reading. Usability is also mentioned as an objective in the study summary, but a separate usability outcome is not listed. The record does not describe any secondary outcomes, subgroup analyses, interim analyses, or statistical testing plan. These items are not reported in the registry record.

Multiplicity arises when several hypotheses or outcomes are tested: the more opportunities there are to identify a nominally unusual result, the more important it becomes to understand whether and how the analysis accounts for that. This is a general statistical issue, not evidence that multiple testing occurred in this study. With no analysis details reported, it is not possible to determine the number of tests performed, whether any adjustment was used, or whether the stated primary outcome was selected before results were examined.

The record also does not report missing-data procedures, exclusions from analysis, or the definition of the analysis population. Enrollment of 368 should not be assumed to equal the number contributing to the primary outcome. The completeness of Dario and YSI measurement pairs, the treatment of unusable readings, and the reasons for any missing measurements are not reported in the registry record. Without these details, neither the endpoint denominator nor the potential influence of missingness can be assessed.

In general, missing data can affect an estimate when the chance that data are missing is related to participant characteristics or measurement outcomes. The appropriate approach depends on the pattern and reason for missingness; the registry entry does not describe either. It also does not report whether all enrolled participants were included in any analysis. Consequently, multiplicity and missing-data handling remain unresolved features of the analysis rather than grounds for assuming a particular bias or correction.

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 0% reporting threshold.

The registry safety entries list the Dario Blood Glucose Monitoring System group with 368 at risk for serious adverse events and zero affected. The entry for other adverse events also lists 368 at risk and zero affected. These are recorded counts in the registry categories; they are not a complete description of how adverse events were defined, solicited, reviewed, or followed over time.

Zero recorded events in these categories should be read narrowly. It means the registry entry reports no affected participants in the listed serious and other event counts. It does not establish that no symptoms or events of any kind occurred, nor does it establish that the device has no risk. The record does not describe surveillance methods or follow-up completeness, so those aspects cannot be evaluated.

Deaths are not reported in the registry record. A missing death value is not the same as a reported count of zero. The record also lists no serious adverse event terms, but does not provide narrative detail about safety monitoring. These limited entries support only a description of what was recorded, not a broader safety conclusion or a comparison with another group.

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

The result that can be described is the study’s intended comparison: laypersons were asked to use the Dario Blood Glucose Monitoring System, and the stated primary endpoint compares their meter readings with YSI readings obtained by a nurse or technician. The registry record identifies a 5 minutes timeframe and a participant-count outcome. It does not report the observed accuracy result, a criterion for accuracy, or an estimate of uncertainty. Thus, the intended question is clear, but the posted record does not show an answer to it.

The record does not establish that readings met a particular standard, that the methods agreed closely, or that any observed agreement was consistent across participants. Such conclusions would require the endpoint definition and numerical results, ideally accompanied by information about uncertainty and the analysis population. The absence of a posted result is not evidence that the device performed well or poorly; it is a limit on what can be concluded from the registry record.

The study also does not provide a randomized treatment comparison. Its single-group classification and allocation listed as NA mean that the YSI reference should not be interpreted as a control treatment arm. The results, if available elsewhere, would need to be interpreted in the context of a measurement comparison and its protocol, rather than as a causal estimate of one treatment versus another.

The usability objective is mentioned, but no usability outcome or finding is reported. Likewise, the safety entries record zero serious and zero other adverse events among 368 at risk, while deaths are not reported. These safety counts do not answer the accuracy question and do not justify conclusions beyond the recorded categories.

In short, the record documents a completed evaluation with a defined broad purpose, but it omits the primary result needed to assess device accuracy. It can establish what was intended to be compared and describe limited design and safety information. It cannot establish the magnitude, precision, or practical significance of the comparison, nor resolve usability or broader safety questions.

13. Why This Trial Matters Statistically

This study is statistically important as an example of the difference between a clearly stated measurement question and a reported analysis that can answer it. The registry identifies a comparison between a layperson’s Dario meter reading and a YSI reference reading. Yet the accuracy criteria, observed count, and statistical analysis are not reported. Without those pieces, the endpoint label alone cannot tell a reader what performance was observed.

The single-group design also illustrates why the role of a comparator must be described precisely. A reference instrument can serve as a benchmark for measurement without constituting a randomized control group. The registry record explicitly identifies the study as nonrandomized and cautions that arms are not a like-for-like control comparison. This distinction prevents readers from interpreting a device-to-reference assessment as a treatment-effect estimate.

For measurement studies, protocol details and analysis choices are central, not incidental. A definition of acceptable agreement, the handling of paired measurements, a clear denominator, and uncertainty estimates are needed to understand a performance result. The record does not report these elements, showing how incomplete outcome reporting can constrain independent statistical interpretation even when the study objective and enrollment are listed.

The safety entries provide a further lesson in scope: counts recorded in registry categories should not be expanded into claims about all possible events or general risk. Similarly, completion status is not a substitute for posted endpoint findings. The record is useful for identifying the study and its stated aims, but its statistical value for evaluating accuracy is limited by the absence of the result and the methods needed to interpret it.

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 central limitation is that the registry record does not report the primary accuracy result. It identifies the comparison and outcome type, but not the observed participant count, the accuracy rule, or an uncertainty estimate. The record therefore cannot support a quantitative assessment of agreement between Dario and YSI readings.

Important protocol details are also not reported in the registry record. These include the criteria used to decide whether a reading was accurate, the measurement procedures for both devices, the handling and matching of readings, and the range of measurements assessed. The timeframe is listed as 5 minutes, but additional timing and protocol details are absent. This limits interpretation of what conditions the comparison represents.

The record does not report participant eligibility details, participant characteristics, or the analysis population. Although enrollment is 368, the number contributing to the endpoint and the completeness of measurements are not given. Missing-data handling, exclusions, and reasons for unavailable or unusable readings are also not described. The influence of these factors on the result cannot be evaluated.

The statistical analysis plan is not reported, and the record lists no analyses. There is no stated model, hypothesis test, confidence interval, or account of how repeated or paired measurements were handled. The summary identifies usability as an objective, but no usability measure or result is listed. These are reporting limitations; they do not establish that the procedures were absent from the study itself.

Finally, the single-group design is not a randomized comparison, and YSI is a reference measurement rather than a like-for-like control arm. The safety entries are limited to registry counts, with deaths not reported and event-collection details absent. Together, these limitations require a narrow interpretation of the record and prevent conclusions about accuracy, usability, or broader safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: User Performance Evaluation for DARIO™ BGMS — NCT02357043.
• Registry record last updated 2021-06-15; status last verified 2016-07.
• Results first posted 2021-06-15.
• 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

NCT02357043 is a completed, single-group evaluation titled “User Performance Evaluation for DARIO™ BGMS,” sponsored by LabStyle Innovations Ltd. The record lists diabetes as the condition, enrollment of 368, a start of 2014-12, and primary completion of 2015-03. Allocation is NA, masking is NONE, and phase is NA.

The stated primary question compares a layperson’s Dario meter reading with a nurse- or technician-obtained YSI reading. The endpoint is described as accuracy, measured in participants, with a timeframe of 5 minutes. The summary also identifies usability by laypersons using device labeling as an objective. The registry record does not report the primary accuracy result, analysis methods, or a separate usability result.

The safety entries report zero serious and zero other adverse events among 368 at risk; deaths are not reported. The registry record lists one outcome measure and no analyses. Its design note cautions that the study is not a randomized comparison and its arms are not a like-for-like control comparison.