Abbott Sensor Based Glucose Monitoring System Paediatric Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Abbott Sensor Based Glucose Monitoring System Paediatric Study (NCT02388815), a na na study. The primary outcome is Point Accuracy.

2. Clinical Question

3. Trial Design

This was a completed, single-group device study of the Abbott Sensor Based Glucose Monitoring System in children with diabetes. Its official title identifies it as a paediatric label-extension study, and its brief summary says that it evaluated point accuracy when the system was used at home. The intervention is named as the FreeStyle Libre Flash Glucose Monitoring System. The registry lists Abbott Diabetes Care as sponsor.

The registry reports enrollment of 89. The study began in 2015-03 and primary completion was in 2015-06. The primary endpoint timeframe was 14 days. The record lists phase as NA, allocation as NA, and masking as NONE. Those entries do not describe a randomized, masked, or parallel-arm comparison. Instead, the primary measurement paired sensor glucose results with fingerstick blood glucose results within the study context.

That design can describe agreement with a reference measurement in the studied setting, but it does not include a separate concurrent control group for comparing treatment strategies. The registry describes a single group and does not report a treatment-effect contrast. The record also does not report the recruitment approach, the detailed visit schedule, participant demographics, or a protocol-level account of how measurements were selected for pairing.

The record identifies one primary outcome measure, Point Accuracy, and gives no analyses in its analysis listing. The endpoint description defines a pooled percentage based on sensor and fingerstick results. It also identifies two participants who were not included in the accuracy analysis but were included in safety analysis. The registry does not report how many paired measurements contributed to the accuracy endpoint, nor does it give a numerical endpoint estimate or confidence interval. Those omissions limit assessment of the study’s precision and of how representative the analysed measurements were.

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.

Before assignment: A total of 89 subjects consented and were enrolled into the study.

Overall Study

Analysis population for the primary outcome, as defined in the registry: One subject withdrew prior to having a sensor applied, another did not perform any blood glucose tests on the FreeStyle Libre. Neither subject could be included in the accuracy analysis, both are included in the safety analysis.

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 Point Accuracy, measured over 14 days.

The primary endpoint, Point Accuracy, was defined as the percentage of glucose results within Consensus Error Grid zone A when sensor-based glucose values were compared with fingerstick blood glucose. The specified timeframe was 14 days. The registry says the calculation used the total number of sensor results and fingerstick blood glucose results, with results in zone A expressed as a percentage of the total results. This describes a result-level measure, rather than a percentage of participants who met an individual accuracy threshold.

The Consensus Error Grid classifies paired measurements by the potential clinical consequences of their disagreement. The registry describes five risk categories, ordered from Zone A through Zone E. Zone A means no effect on clinical action; the remaining zones represent progressively greater potential for altered clinical action or risk. This framework is used because numerical closeness alone does not convey whether a discrepancy could matter in a clinical decision. The grid uses paired values: sensor-based glucose is the test value and fingerstick blood glucose is the reference value.

The endpoint is intended to describe how often the paired glucose results fell into the category defined as having no effect on clinical action. The registry record does not report the calculated percentage or its 95% confidence interval. It also does not report the number of paired readings included, so neither the observed point accuracy nor its statistical precision can be judged from the recorded results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a proportion constructed from paired measurement results. A sensor-based glucose result is compared with a fingerstick blood glucose result, and the pair is classified on the Consensus Error Grid. The endpoint counts results in zone A and expresses them as a percentage of all results used in the calculation, as described in the registry. This is a descriptive measure of how often the observed pairs fell into a particular category.

What does the confidence interval represent?

General statistical explanation: a confidence interval describes uncertainty around an estimate, under the assumptions of the method used to calculate it. For a proportion, the interval gives a range of values compatible with the observed data and the calculation procedure. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. The registry specifies a 95% confidence interval as the endpoint’s dispersion measure, but the interval itself is not reported. Without the estimate and interval, precision cannot be evaluated.

Why does pairing matter?

General statistical explanation: measurements must be paired in a way that makes the comparison meaningful. A sensor result and a reference result should correspond to the same relevant measurement occasion under the study’s rules. The registry identifies sensor-based values and fingerstick blood glucose as the compared measurements, but does not explain the detailed pairing rules, timing tolerances, or handling of unmatched readings. These details can affect which pairs enter the calculation and how well the endpoint reflects the intended measurement comparison.

General statistical explanation: repeated measurements from the same person are often correlated. They do not necessarily provide as much independent information as the same number of measurements from different people. When a proportion is based on many observations per participant, an analysis that treats every result as independent may understate uncertainty if within-person dependence is present. This issue is sometimes addressed with methods that account for clustering or with participant-level summaries. The registry describes calculation across glucose results but does not report whether within-participant dependence was addressed. It also does not report the number of results contributing to the estimate, so the extent of this issue cannot be assessed.

What does the error grid add?

General statistical explanation: a measurement error can be described by its numerical size, but the clinical importance of a discrepancy can depend on where the values fall and what action might follow. An error grid groups paired values according to potential consequences. In this study’s description, Zone A is the category with no effect on clinical action. The other zones represent increasing levels of potential effect or risk, as assessed in the grid framework described by the registry. A zone classification is not itself a probability of harm, and the registry does not report the distribution of results in each category.

The record’s endpoint is a result-level percentage, not a participant-level binary outcome. These summaries answer different questions. A result-level percentage concerns the share of measurements in zone A. A participant-level outcome would instead classify each person according to a defined criterion, which is not described as the primary endpoint. Because participants may contribute different quantities of data, the result-level summary may give more influence to participants with more recorded pairs. The registry does not report participant-level contributions or a sensitivity analysis using a different summary.

What can be inferred from the design?

General statistical explanation: a single-group measurement study can describe agreement between a device and a reference method in the settings and population studied. It does not create a randomized contrast between separate groups. In this record, allocation is NA, masking is NONE, and the model is single-group. The endpoint compares measurement methods, but the registry does not describe blinded assessment. The absence of a separate control group is not a flaw for every accuracy question; it does mean that comparative treatment-effect questions are outside the design.

The registry labels the primary outcome’s dispersion as a 95% confidence interval, but does not supply a numerical interval or the method used to calculate it. It does not report a statistical analysis plan, adjustment strategy, or assumptions for the interval. General statistical explanation: the suitability of a confidence interval depends on the structure of the data and the method’s assumptions. For clustered or repeated measurements, a method that accounts for dependence may be needed. No specific method can be attributed to this study from the registry record.

The record lists one primary outcome measure and no analyses in its analysis listing. That does not establish whether other analyses occurred outside the registry entry; it means the registry record does not report them. No p-value, model-based estimate, or inferential comparison is reported. As a result, the registered endpoint definition can be explained, but the analysis implementation and numerical findings cannot be independently assessed from this record.

Planning calculations are conceptually different from study findings. General statistical explanation: a planning illustration based on an observed effect can show how a hypothetical future study might be sized under stated assumptions. It is not an estimate of the trial’s observed power and does not replace the outcome estimate or its uncertainty. The assumptions described for planning illustrations are not the study’s own design justification. The registry record does not report the trial’s sample-size justification, so the enrollment cannot be interpreted as evidence that the study had a particular planned precision or power.

10. Multiplicity, Missing Data and Analysis Populations

The registry record identifies Point Accuracy as the primary outcome measure and reports one outcome measure, but it does not report a statistical analysis plan. It also does not list any analyses. There is no description of multiple primary comparisons, adjustment for multiple testing, a testing hierarchy, or interim analyses. These features are therefore not reported in the registry record; their absence from the registry entry should not be taken as proof that no such procedures were used outside the entry.

Multiplicity matters when a study makes several statistical tests or examines multiple outcomes, because the chance of at least one apparently unusual result can increase as the number of tests grows. General statistical explanation: prespecified priorities and suitable adjustments can help control how results are interpreted when many comparisons are made. In this record, no inferential results are listed, so there is no reported family of tests to evaluate and no multiplicity adjustment to assess.

The registry identifies two exclusions from the accuracy analysis. One participant withdrew before a sensor was applied; another did not perform any blood glucose tests on the FreeStyle Libre. Both participants were included in the safety analysis. These stated exclusions explain why enrollment and the accuracy analysis population are not identical, but the record does not report the number of paired measurements analysed.

The registry does not report how other missing or unusable measurements were handled, whether all eligible pairs were included, or whether any sensitivity analyses were conducted. It also does not describe an intention-to-treat or per-protocol analysis population. These population definitions and missing-data procedures are important for understanding a result-level endpoint. Since the endpoint estimate itself is not reported, the possible effect of missing measurements on the findings cannot be evaluated.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: painful right leg (1.1%).

The safety record reports enrollment of 89 in the FreeStyle Libre Flash Glucose Monitoring System group. It records 1 participant with a serious adverse event and 15 participants with other adverse events. Painful right leg is listed among the serious adverse-event terms, with a reported percentage of 1.1%. The registry record does not report a death count.

These figures should be read as safety counts from the registry, not as evidence that the device caused an event. A single-group safety listing does not provide a randomized comparison for estimating whether event rates differ from another intervention or from usual care. The record does not provide event narratives, timing, duration, severity details beyond the serious-event classification, or an assessment of relatedness. It also does not report the total number of events for each participant or the observation time used for safety reporting.

The two participants excluded from accuracy analysis were included in the safety analysis, according to the registry. This illustrates that the analysis population can depend on the outcome: a participant may contribute to safety surveillance without contributing to the measurement-accuracy calculation. The safety counts and the accuracy endpoint therefore address different questions and should not be treated as interchangeable evidence.

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

This registry entry documents a study intended to assess point accuracy of the Abbott Sensor Based Glucose Monitoring System during home use by children with diabetes. It identifies the FreeStyle Libre Flash Glucose Monitoring System as the intervention, fingerstick blood glucose as the reference method, and the percentage of results in Consensus Error Grid zone A as the primary endpoint. The endpoint timeframe is 14 days. These details clarify the measurement question and the category the study intended to summarize.

What the record does not provide is the numerical percentage of results in zone A or its 95% confidence interval. Consequently, it does not show the observed proportion, the uncertainty around that estimate, or the distribution across the remaining error-grid zones. The endpoint definition alone cannot establish how the device performed in this study. The absence of a posted numerical result should not be interpreted as a particular outcome.

The design also sets boundaries on the conclusions. A single-group measurement study comparing sensor readings with a fingerstick reference is not a randomized comparison of treatment strategies. The record does not report a separate control group or a treatment-effect estimate. It therefore cannot answer comparative questions that require such a contrast. Masking is listed as NONE, and allocation as NA.

The accuracy analysis excluded two participants for the reasons stated in the registry, while both were included in safety analysis. The endpoint calculation is described as based on glucose results, but the number of paired results and the handling of other missing readings are not reported. The record also does not describe whether repeated measurements within participants were accounted for statistically. These gaps limit interpretation of both the endpoint population and its precision.

The safety listing reports serious and other adverse events, but it does not establish that the device caused them. Without a comparator and further event details, the counts should be understood as descriptive registry information. Overall, the record communicates the study’s question and basic design, but the missing numerical accuracy result prevents an assessment of the primary outcome’s magnitude.

13. Why This Trial Matters Statistically

This study illustrates why accuracy outcomes need more than a device name and an endpoint label. The endpoint is defined as the proportion of paired sensor and fingerstick results within a particular error-grid zone. That definition makes clear what the investigators intended to summarize, while also showing why the denominator and the pairing rules matter. For a result-level measure, the number and distribution of readings across participants can affect how the summary should be interpreted.

The error-grid framework also highlights a broader statistical point: measurement agreement is not always adequately described by a single average difference. Categorizing paired values by potential clinical consequences provides one way to distinguish discrepancies that have different implications. In this study, Zone A is defined as having no effect on clinical action. The registry does not report the observed proportion in that zone, so the framework’s relevance can be explained, but its result cannot be evaluated.

The record is also a reminder that design and reporting answer separate questions. A single-group design can be suited to comparing a device measurement with a reference method, but it does not offer a randomized treatment comparison. Further, a defined confidence-interval measure is useful only when its estimate and interval are reported. Here, neither the numerical point-accuracy estimate nor its interval appears in the registry record.

Finally, analysis populations can differ by outcome. Two participants were excluded from accuracy analysis for stated measurement-related reasons but remained in safety analysis. This is not inherently inconsistent: accuracy requires usable paired measurements, while safety reporting can include participants without such measurements. Clear reporting of those populations, the number of analysed pairs, and the treatment of repeated or missing readings is important for evaluating the reliability and scope of an accuracy estimate.

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 principal limitation of the registry record for interpreting this study is that it does not report the primary endpoint’s numerical estimate or 95% confidence interval. The outcome definition is available, but the observed point accuracy and its precision cannot be assessed. The record also does not report the number of paired sensor and fingerstick results contributing to the endpoint, which leaves the size of the measurement dataset unclear.

The endpoint is calculated across glucose results, but the registry does not describe how measurements were paired, whether readings had to meet timing criteria, or how unmatched or unusable readings were handled. It does not report whether statistical methods accounted for repeated measurements within participants. These omissions make it difficult to evaluate the assumptions behind any result-level percentage and confidence interval.

The record identifies two participants excluded from accuracy analysis and says both were included in safety analysis. It does not report whether there were other missing readings, the characteristics of participants with incomplete measurement data, or sensitivity analyses to evaluate the influence of missingness. Participant characteristics beyond the condition are also not reported, limiting assessment of how broadly the study population represents children with diabetes.

The study is single-group, and masking is listed as NONE. The registry does not report a separate randomized comparator, detailed measurement procedures, or an analysis plan. It also does not provide the trial’s sample-size justification. As a result, neither the intended precision nor the analytic choices behind the endpoint can be evaluated from the registry entry. The safety information is similarly limited by the absence of event timing, relatedness assessments, and comparative data.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Abbott Sensor Based Glucose Monitoring System Paediatric Study — NCT02388815.
• Registry record last updated 2016-08-11; status last verified 2016-07.
• Results first posted 2016-04-12.
• 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

The registry record describes a completed, single-group paediatric device study sponsored by Abbott Diabetes Care. It lists enrollment of 89, a start date of 2015-03, primary completion in 2015-06, and a 14 days timeframe for the primary endpoint. The intervention was the FreeStyle Libre Flash Glucose Monitoring System, evaluated for point accuracy against fingerstick blood glucose.

The primary outcome was the percentage of glucose results in Consensus Error Grid zone A, with a 95% confidence interval specified as the dispersion measure. The registry does not report the numerical endpoint estimate or its confidence interval, and no analyses are listed. One participant withdrew before sensor application and another performed no blood glucose tests on the FreeStyle Libre; neither was included in accuracy analysis, while both were included in safety analysis.

The safety listing reports 1 participant with a serious adverse event and 15 with other adverse events. The record lists Painful right leg at 1.1% among serious-event terms. A death count is not reported in the registry record.