Systemic Pharmacokinetics Following Intravitreal Injections of Anti-VEGF: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Systemic Pharmacokinetics Following Intravitreal Injections of Anti-VEGF (NCT02118831), a non-randomized phase 1, phase 2 study. The primary outcome is Serum Pharmacokinetics Following Treatment From 1st and 3rd Doses.

2. Clinical Question

In statistical terms, this is a pharmacokinetic and biomarker study, not a direct test of visual or other clinical benefit. Its stated aim was to examine systemic exposure after injections into the eye and assess circulating free VEGF. Those measurements can describe drug levels and biomarker patterns, but the record does not provide evidence about clinical outcomes.

3. Trial Design

This completed Phase 1 and Phase 2 study is described as a prospective, non-randomized, unmasked, parallel study. Enrollment was 56. The registry lists California Retina Consultants as the sponsor, a start date of 2012-03, and primary completion in 2014-02. These design details describe how the record classifies the study; they do not by themselves establish that treatment groups were comparable.

Participants received one of three agents: aflibercept, bevacizumab or ranibizumab. Blood sampling was planned following the first and third dose of standard-care therapy for each group. The primary outcome description specifies measurement of maximum serum levels after those injections, up to 28 days following each treatment. The primary timeframe is listed as up to 4 months. The record does not give further details about the exact sampling schedule, dose amounts, treatment intervals or assay procedures.

Because allocation was non-randomized, the groups should not be read as if assignment had balanced known and unknown participant characteristics. The registry explicitly flags that the arms are not a like-for-like control comparison. Any apparent differences could reflect treatment, differences between the people receiving each treatment, or other factors not described in the record. The allocation method and any adjustment strategy are not reported in the registry record.

The study is unmasked, so masking is listed as none. Whether participants, laboratory staff or outcome assessors knew treatment assignments in practice, and whether any steps were taken to limit measurement bias, are not reported in the registry record. The record lists two outcome measures and zero analyses. It gives the endpoint descriptions but no numerical results for either outcome. Consequently, the available record supports an account of the intended design and measurements, not a comparison of observed pharmacokinetic or biomarker effects.

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 Serum Pharmacokinetics Following Treatment From 1st and 3rd Doses, measured over Up to 4 months.

The primary endpoint is titled serum pharmacokinetics following treatment from the first and third doses. It is a continuous measure summarized as a mean, with standard deviation identified as the dispersion measure and nanomolar (nM) as the unit. The description says maximum serum levels of ranibizumab, bevacizumab or aflibercept will be measured after the first and third injections, up to 28 days following each treatment.

Pharmacokinetic measurements describe how much drug is present in the systemic circulation after treatment and how those measured levels vary over the stated observation period. In general, serum concentration measurements can help characterize systemic exposure; measuring after more than one dose can also describe levels following different points in a treatment course. This is a general explanation of the endpoint type, not a claim about what this study observed.

The endpoint is not a clinical outcome such as vision, symptoms or disease progression. The registry record does not report the actual serum-level means, standard deviations, sample counts for the outcome, or numerical comparisons between drug groups. It therefore does not allow readers to judge the observed concentrations or their precision. The record also does not describe the laboratory assay, its measurement properties, or how maximum levels were selected from the post-injection samples. Those details are not reported in the registry record.

The registry lists a timeframe of up to 4 months. The secondary outcome concerns change in minimum serum free VEGF from baseline to Month 4, described as one month after the last treatment. That is a distinct biomarker endpoint and should not be confused with the primary serum drug-level measure.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

This discussion explains the statistical ideas relevant to the study design and stated outcomes. The registry record does not describe a detailed statistical analysis plan, so general explanations below should not be mistaken for methods that the investigators necessarily used.

What does a continuous endpoint mean?

The primary outcome is a continuous serum concentration measured in nM. Continuous measurements can take a range of values rather than belonging only to categories. The registry identifies the mean as the summary parameter and standard deviation as the measure of dispersion. In general, the mean gives a summary of the center of a set of measurements, while the standard deviation describes their spread. A mean alone does not show whether observations are tightly clustered or widely dispersed. The registry record does not report the endpoint's observed mean or standard deviation.

Why measure more than once?

The plan describes maximum serum drug levels following the first and third injections, with measurements up to 28 days after each treatment. In general, repeated sampling after a dose can describe how measured concentration changes over time, while measuring at more than one point in a treatment course can distinguish patterns after earlier and later doses. These are general reasons for pharmacokinetic sampling. The record does not give the actual sampling times, the method used to select a maximum, or the observed concentration-time pattern.

How should a confidence interval be read?

General explanation: a confidence interval expresses the uncertainty around an estimated quantity using a range of values compatible with the data and the calculation method. A narrow interval indicates greater precision than a wide interval, all else equal. It is not a guarantee that the true value lies within the particular interval. No confidence intervals are reported for the outcomes in the registry record, so their precision cannot be assessed from this record. A p-value, if reported, would address compatibility of the data with a specified statistical model or null hypothesis; it would not by itself express the size or clinical importance of an effect. No outcome p-values are reported.

What does non-randomized allocation imply?

General explanation: random allocation is one way to make treatment groups comparable, on average, with respect to measured and unmeasured baseline characteristics. In a non-randomized study, assignment may be related to participant features, clinical circumstances or other factors. That can make a simple group comparison difficult to interpret as an effect of treatment alone. The registry explicitly notes that this study is not a randomized comparison and that its arms are not a like-for-like control comparison. It does not report the process used to choose treatment or an adjustment model. Readers should therefore avoid treating a difference between groups as an unconfounded treatment effect.

What does mean and standard deviation leave out?

General explanation: a mean and standard deviation summarize a distribution but do not show all its features. If data are skewed, contain extreme values, or differ in variability between groups, these summaries may not fully describe the observed pattern. Concentration measurements can be assessed using graphical or model-based methods, but the record does not specify such methods or report distributional diagnostics. There is no basis to assert that the observed measurements were skewed or that a particular transformation or model was used.

Why can over-dispersion matter?

General explanation: over-dispersion occurs when variation in the data is greater than a statistical model assumes. If a model understates variation, standard errors and uncertainty intervals may be too small, making results appear more precise than they are. This concept is especially relevant to count outcomes and some regression models; it should not be assumed to apply to this study's continuous primary endpoint. The registry record does not identify a model or report a dispersion assessment. The primary outcome is described by a mean and standard deviation, but the actual values are not reported.

How should planning illustrations be understood?

General explanation: sample-size calculations can illustrate how many participants per arm might be needed under specified assumptions about the effect to detect, significance level, allocation and statistical model. They are planning illustrations, not observed power and not a substitute for the study's actual results. The calculation assumptions stated for this page use a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. The registry record does not report that these were the trial's own design assumptions or its sample-size justification. The record does not report a protocol-based sample-size rationale. Numerical planning values should not be interpreted as the number enrolled or as evidence that a result is likely to be significant.

The registry record lists zero analyses. It does not specify a statistical test, a model for repeated measurements, a method for handling correlation between measurements from the same participant, or an approach to adjustment for group differences. Those details are not reported in the registry record. The explanations above describe concepts that can help readers assess statistical claims if such methods and results appear in posted tables or plots; they do not fill in the missing analysis plan.

10. Multiplicity, Missing Data and Analysis Populations

The record lists two outcome measures: the primary serum pharmacokinetic endpoint and a secondary measure of change in minimum serum free VEGF from baseline to Month 4. It does not describe how many statistical tests were planned, whether the outcomes were tested at multiple time points, or whether any multiplicity adjustment was planned. These details are not reported in the registry record.

In general, multiplicity arises when several outcomes, time points, treatment comparisons or analyses are examined. Considering many tests can increase the chance of finding an apparently notable result by chance. Methods for addressing multiplicity depend on the questions and analysis plan. No such method is reported, and the record lists zero analyses, so there are no reported test results on which to assess this issue.

The registry record does not report outcome-specific participant counts, missing measurement counts, reasons for missingness, or how missing data were handled. It also does not state whether the primary analysis included all enrolled participants, only participants with available measurements, or another analysis population. These points are not reported in the registry record and should not be inferred from the overall enrollment figure or safety denominators.

In general, missing measurements can affect both the estimated result and its precision, particularly if the availability of measurements is related to participant characteristics or outcomes. That is a general concern, not evidence that missingness occurred in this study. The registry record does not describe imputation, sensitivity analyses, or exclusions. It also does not identify a prespecified intention-to-treat or per-protocol analysis population. Without those details and outcome results, readers cannot assess whether the analysis addressed missingness or multiplicity.

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 posted safety summary lists serious adverse events for aflibercept among 21 participants at risk, with 0 affected; for bevacizumab among 15 participants at risk, with 0 affected; and for ranibizumab among 20 participants at risk, with 0 affected. The summary also lists 0 participants affected by other adverse events in each of those groups, using the same group-specific numbers at risk.

These are counts in the posted safety summary, not estimates of comparative risk. In general, a zero count means no events of that category were recorded in the summarized group; it does not establish that an event is impossible or that treatments have equivalent safety. The record does not report exposure-adjusted rates, a comparison test, follow-up completeness, or uncertainty intervals for these counts.

The deaths field is null for each group, and the serious-event term list is empty. Those entries do not establish that there were no deaths or that no events were monitored; the death information is not reported in the registry record. The safety figures should be read as descriptive registry counts, with the limitations of the available reporting and the non-randomized group allocation.

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

This study asks a focused pharmacokinetic question: what serum levels of ranibizumab, bevacizumab and aflibercept are measured after intravitreal injections, and how do minimum serum free VEGF levels change over the stated follow-up? Its design and endpoint descriptions make clear that the intended evidence concerns systemic drug levels and a circulating biomarker. Those measures are distinct from direct clinical outcomes.

The registry record does not include numerical results for either outcome. It therefore does not show the observed means, variability, changes, differences between drug groups, or the precision of any estimates. No conclusion about the direction or size of the outcome findings can be drawn from the record as. General interpretations of pharmacokinetic or biomarker measurements cannot replace the missing results.

The design also limits what a group comparison could establish. Allocation was non-randomized, and the record cautions that the arms are not a like-for-like control comparison. In general, differences between groups can reflect underlying differences in the participants or treatment selection as well as differences associated with treatment. The registry record does not report enough detail to determine whether those factors were measured or adjusted for.

The safety summary reports zero serious adverse events and zero other adverse events in each treatment group, for the stated numbers at risk. These descriptive counts do not demonstrate equivalence or rule out events beyond those captured in the summary. Death information is not reported in the registry record.

Accordingly, the study should be understood as a completed prospective investigation with specified drug-level and biomarker measurements, rather than as a documented demonstration of clinical benefit or harm. The registry record provides no basis for medical decisions or for claims about comparative effectiveness. It also does not provide a statistical analysis plan or outcome estimates that would allow a reader to judge the strength and precision of the intended comparisons.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it puts systemic pharmacokinetics and a circulating biomarker at the center of a study of drugs administered by intravitreal injection. The primary endpoint is a continuous serum concentration, while the secondary endpoint concerns a change in minimum free VEGF. These outcomes require different interpretations: one describes measured drug exposure and the other a biomarker change. Neither is interchangeable with a clinical outcome.

The study also illustrates why design information matters when comparing groups. A parallel structure can organize observations by treatment, but non-randomized allocation does not ensure that the groups are comparable. The registry explicitly cautions that these arms are not a like-for-like control comparison. This makes confounding and treatment selection important interpretive concerns, even before considering the missing outcome results.

Repeated sampling after the first and third doses offers a framework for describing concentrations at more than one point in treatment. In general, such measurements can be informative about systemic exposure over time. Their interpretation depends on the actual sampling schedule, assay, participant-level observations and analysis method. The registry record does not report these details or the numerical results, so the statistical questions are more fully specified than the evidence shown in this record.

Finally, the page separates observed evidence from planning illustrations. A sample-size calculation based on an observed effect can be useful for exploring planning assumptions, but it is not observed power and does not recover missing outcome estimates. The record's lack of reported analyses and outcome values is itself important: readers should distinguish a described research question from a result that can be independently evaluated.

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 information is that it describes the endpoints but does not report their numerical results. The primary outcome's mean and standard deviation are not shown, and no results are given for the secondary free-VEGF change. Confidence intervals, p-values and outcome-specific participant counts are also not reported in the registry record. This prevents assessment of the magnitude, direction and precision of the measured outcomes.

Non-randomized allocation limits causal interpretation of comparisons among aflibercept, bevacizumab and ranibizumab. The record itself says the arms are not a like-for-like control comparison. It does not describe treatment selection, baseline characteristics, statistical adjustment or other approaches to comparability. The unmasked classification is also relevant, while details about blinding of laboratory or outcome assessment are not reported in the registry record.

Further methodological details are unavailable, including the exact blood-sampling schedule, assay characteristics, handling of repeated observations, analysis populations and missing-data methods. The record does not give a sample-size justification, interim-analysis information or a detailed statistical plan. The listed conditions include age-related macular degeneration, diabetic macular edema and retinal vein occlusion, while the brief study summary focuses on neovascular age-related macular degeneration; the relationship between those entries and the enrolled population is not reported in the registry record.

The safety summary is descriptive and does not include uncertainty estimates or comparative analyses. The death entries are not reported. Together, these limitations mean that the registry record is useful for understanding the intended design and measures, but it cannot support a detailed statistical evaluation of the study's outcome findings.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Systemic Pharmacokinetics Following Intravitreal Injections of Anti-VEGF — NCT02118831.
• Registry record last updated 2016-05-19; status last verified 2016-04.
• Results first posted 2016-05-19.
• 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.

18. Record Summary

This completed Phase 1 and Phase 2 study enrolled 56 participants and is classified as prospective, non-randomized, unmasked and parallel. Its stated aim was to measure serum drug levels and plasma free VEGF following intravitreal ranibizumab, bevacizumab or aflibercept. Blood sampling was planned after the first and third doses of standard-care therapy.

The primary endpoint concerns maximum serum drug levels, measured in nM, after those injections and up to 28 days following each treatment; the stated timeframe is up to 4 months. The secondary outcome is change in minimum serum free VEGF from baseline to Month 4. The record lists two outcome measures and zero analyses, but reports no numerical results for either outcome.

The safety summary lists zero serious adverse events and zero other adverse events in each treatment group. The record warns that the non-randomized arms are not a like-for-like control comparison. Detailed analysis methods, missing-data handling and outcome-specific participant counts are not reported in the registry record.