This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Observational Data Analysis in EuroSIDA (MK-0518-058) (NCT01078233), a registered phase not stated study. The primary outcome is Incidence of Malignancy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01078233 |
| Phase | Phase not stated |
| Condition | HIV-1 Infections |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 6617 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Merck Sharp & Dohme LLC |
| Results posted | Yes |
2. Clinical Question
Population
People with HIV-1 infection included in the EuroSIDA study cohorts. The registry record reports an enrollment of 6617, but does not report the number of participants in each cohort or the characteristics of the analyzed participants.
Intervention
The Raltegravir Cohort included participants who started raltegravir on or after 21 December 2007 and had at least 1 month of prospective follow-up in that cohort. This is an exposure-defined group in an observational analysis, not a randomly assigned treatment group.
Comparator
The Historical Cohort included participants who started a new antiretroviral drug as part of combination antiretroviral therapy on or after 1 January 2006 and before 21 December 2007, with no previous exposure to that drug and at least 1 month of prospective follow-up. The Concurrent Cohort included participants who started a new antiretroviral drug other than raltegravir on or after 21 December 2007, also with no previous exposure to that drug and at least 1 month of prospective follow-up. These cohorts are not like-for-like control groups.
Primary question
What was the incidence rate of first occurrence of any malignancy, including AIDS-defining and non-AIDS-defining malignancies, in the cohorts during their specified follow-up? The outcome was to be expressed as events per 100 person-years of follow-up. The registry record does not report the cohort-specific rates or their confidence intervals, so the size and precision of any observed differences cannot be described from this record.
3. Trial Design
NCT01078233 is an observational data analysis in the EuroSIDA study. Its stated objective was to monitor health outcomes associated with antiretroviral drugs in a population of people with HIV. The record lists the study as completed. The listed study dates are 2008-05-05 for study start and 2014-03-06 for primary completion.
The analysis distinguishes a Raltegravir Cohort from a Historical Cohort and a Concurrent Cohort. Cohort membership was defined by starting raltegravir or another new antiretroviral drug during specified calendar periods, together with eligibility requirements that included at least 1 month of prospective follow-up. Participants in the Historical Cohort started a new drug before 21 December 2007; the Raltegravir and Concurrent Cohorts began drug exposure on or after that date. The descriptions in the registry record are incomplete, so further eligibility details are not reported in the registry record.
This is not a randomized comparison. Treatment allocation is not stated, and the registry record cautions that the arms are not a like-for-like control comparison. The historical cohort also comes from a different calendar period than the raltegravir and concurrent cohorts. These design features matter when interpreting differences: cohort membership may reflect clinical decisions and participant characteristics as well as drug exposure, and the groups may have had different opportunities for observation.
The primary outcome was malignancy incidence. Follow-up was defined differently across cohorts: up to 24 months for the Historical Cohort, from January 2006 to December 2007, and up to 68 months for the Raltegravir and Concurrent Cohorts, from December 2007 to July 2013. The primary analysis population was described as intention-to-treat, with follow-up continuing to the cohort’s end-of-follow-up period regardless of whether raltegravir or other drugs were discontinued.
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: The analyses in this study are based on data collected from a cohort of HIV-1-infected participants in a setting of routine clinical care in Europe (EuroSIDA Cohort Study). Participants could contribute data to more than one cohort, but no overlap in follow-up time was allowed.
Overall Study
| Stage | Raltegravir Cohort Only | Historical and Raltegravir Cohorts Only | Historical Cohort Only | Historical and Concurrent Cohorts | Concurrent Cohort Only | Concurrent and Raltegravir Cohorts Only |
|---|---|---|---|---|---|---|
| STARTED | 656 | 296 | 1681 | 631 | 3199 | 154 |
| COMPLETED | 656 | 296 | 1681 | 631 | 3199 | 154 |
| NOT COMPLETED | 0 | 0 | 0 | 0 | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Intention-to-Treat analysis included follow-up until the end of the follow-up period for the cohort, regardless of whether or not raltegravir or other drugs were discontinued.
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.
Only the first 6 of 7 groups are shown.
| Characteristic | Unit | Raltegravir Cohort Only | Historical and Raltegravir Cohorts Only | Historical Cohort Only | Historical and Concurrent Cohorts | Concurrent Cohort Only | Concurrent and Raltegravir Cohorts Only |
|---|---|---|---|---|---|---|---|
| Participants analysed | 656 | 296 | 1681 | 631 | 3199 | 154 | |
| Age, Continuous | Years | 49 (44 to 55) | 49 (44 to 55) | 44 (39 to 50) | 47 (41 to 53) | 42 (34 to 50) | 50 (45 to 57) |
| Sex: Female, Male: Female | Participants | 176 | 72 | 422 | 174 | 873 | 27 |
| Sex: Female, Male: Male | Participants | 480 | 224 | 1259 | 457 | 2326 | 127 |
6. Primary Endpoint
The registry lists the primary outcome as Incidence of Malignancy, measured over Historical Cohort: up to 24 months (January 2006 to December 2007); Raltegravir and Concurrent Cohorts: up to 68 months (December 2007 to July 2013).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Events per 100 person-years of follow-up |
| Endpoint classification | Event-Rate Endpoint |
The primary endpoint was incidence of malignancy, expressed as events per 100 person-years of follow-up. It covered all-type malignancy, including both AIDS-defining and non-AIDS-defining malignancy. For each participant, only the first occurrence of any malignancy type was counted. Thus, the endpoint is a rate based on events and accumulated follow-up time, not simply a proportion of participants who experienced an event.
Person-time rates are useful in cohort studies when participants may contribute different amounts of follow-up. The rate relates the number of qualifying events to the time participants were observed and at risk under the endpoint definition. This can make the measure more interpretable when follow-up duration varies, although it does not by itself make groups comparable or remove confounding.
For this analysis, follow-up windows differed by cohort. The Historical Cohort had up to 24 months of follow-up, while the Raltegravir and Concurrent Cohorts had up to 68 months. The registry record does not report the observed event counts, person-time totals, incidence rates, or 95% confidence intervals. The endpoint definition is therefore available, but its estimated values and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record specifies a clinically relevant safety outcome and how it was to be counted, but it does not provide the primary outcome results. It describes malignancy incidence as events per 100 person-years and states that only each participant’s first malignancy occurrence was counted. It also specifies a 95% confidence interval as the measure of dispersion. However, no cohort-specific rate estimates, event counts, person-time totals, or confidence interval limits are reported in the registry record.
Without those estimates, it is not possible to describe the direction or magnitude of the observed rates, compare their precision, or determine whether the data are compatible with a wide or narrow range of underlying rates. The enrollment figure of 6617 does not fill this gap: enrollment alone does not indicate how many participants contributed to each cohort, how much follow-up they contributed, or how many malignancy events occurred.
Even if cohort rates were available, this design would require cautious interpretation. Participants were not randomly assigned, and the registry record explicitly states that the arms are not a like-for-like control comparison. Cohort membership was related to the timing and type of antiretroviral drug initiation. Differences in participant characteristics, clinical circumstances, background care, and observation time could therefore contribute to differences in the measured rates. The record does not report adjustment methods or an analysis that addresses such differences.
The specified intention-to-treat approach retained follow-up through the end of the cohort follow-up period regardless of whether the relevant drugs were discontinued. That definition clarifies how follow-up was intended to be handled, but it does not supply information about actual follow-up completeness, treatment changes, or missing outcome data.
The registry record lists no statistical analyses. It also does not report a statistical analysis plan, multiplicity adjustment, or handling of missing data. Accordingly, the posted record supports description of the study question, endpoint definition, and cohort structure, but not a conclusion about the observed malignancy incidence or a causal effect of raltegravir.
9. Statistical Methods Explained
What does an incidence rate represent? The primary endpoint is an event rate per unit of exposure time, with the unit stated as events per 100 person-years of follow-up. In general, a person-time rate relates qualifying events to the total time participants contribute while being observed for the outcome. It is not the same as a risk or proportion over a fixed period: participants can contribute different follow-up durations, and the rate uses that exposure time in its denominator. The registry record does not report the event counts or person-time values used for this endpoint.
Why count only the first malignancy? The endpoint definition counts only the first occurrence of any malignancy type for each participant. This makes the outcome a first-event measure rather than a count of every subsequent malignancy. It also means that the endpoint does not describe recurrence or the total burden of multiple malignancy events. The registry record does not report how malignancy diagnoses were ascertained or classified beyond including AIDS-defining and non-AIDS-defining malignancies.
What does a confidence interval convey? The registry record specifies a 95% confidence interval for the rate. In general, a confidence interval communicates statistical uncertainty around an estimate: narrower intervals indicate greater precision under the method used, while wider intervals indicate less precision. It does not show the range of individual participant outcomes and does not, by itself, resolve bias or confounding. The interval limits and the method used to calculate them are not reported in the registry record.
Why does over-dispersion matter? In general, a basic count model can assume that variability follows a particular relationship to the mean. If the observed event counts vary more than that assumption allows, over-dispersion can make standard errors too small and confidence intervals too narrow when it is ignored. Alternative variance methods can account for extra variability. The registry record does not identify a count model, state whether over-dispersion was assessed, or describe a variance adjustment, so no claim can be made about how this issue was handled.
How should the cohort structure affect interpretation? The three groups are observational cohorts defined by drug initiation and calendar period. The Historical Cohort began a new antiretroviral drug before 21 December 2007, whereas the Raltegravir and Concurrent Cohorts began treatment on or after that date. The Concurrent Cohort was defined by starting a new antiretroviral drug other than raltegravir. These are not randomized assignments, and the registry record states that the arms are not a like-for-like control comparison. General statistical interpretation therefore distinguishes an association between cohort membership and an outcome rate from a causal treatment effect.
The follow-up windows also differ: up to 24 months for the Historical Cohort and up to 68 months for the Raltegravir and Concurrent Cohorts. Rates account for exposure time in their denominator, but that alone cannot address differences in calendar time, participant mix, outcome ascertainment, or other systematic features of the cohorts. The registry record does not report adjusted estimates or covariates used in an adjustment.
What do the planning assumptions mean? The record describes planning illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is specified as a fraction of the observed effect. For time-to-event illustrations, the stated calculation concerns total events using the Schoenfeld approach; other illustrations are expressed as participants per arm. These are planning assumptions, not observed study outcomes or observed power. The registry record does not report the actual outcome estimates needed to interpret the illustrations, and does not report the trial’s own sample-size justification.
The record lists no statistical analyses, and does not report model details, hypothesis tests, covariate adjustment, interim analyses, or the statistical analysis plan. Those omissions limit assessment of how estimates were produced and what comparisons were prespecified. General methodological explanations describe what such methods mean, not methods confirmed to have been used in this analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists 4 outcome measures, but the registry entries describe only the primary malignancy endpoint. Further outcome definitions are not reported in the registry record. No statistical analyses are listed. The record does not report how multiple outcomes or comparisons were handled, whether any multiplicity adjustment was planned, or whether the primary endpoint was selected from a broader analysis plan.
Missing-data procedures are not reported in the registry record. It does not describe the amount or pattern of missing outcome information, incomplete follow-up, censoring rules beyond the stated cohort follow-up period, or methods for handling missing covariates. The primary population is described as intention-to-treat: follow-up continued until the end of the cohort’s follow-up period regardless of whether raltegravir or other drugs were discontinued. That definition addresses discontinuation in the stated population, but does not establish that all outcomes or follow-up information were complete.
The record does not report how deaths were handled in the malignancy analysis or whether competing events were considered. It also does not give the number of participants or events included in each cohort-specific analysis. These details would be important for evaluating the completeness and interpretation of the rate estimates, but are not reported in the registry record.
11. What the Result Does, and Does Not, Mean
The registry record establishes that the analysis was designed to monitor health outcomes associated with antiretroviral drugs in people with HIV, with malignancy incidence as the primary outcome. It specifies a first-occurrence endpoint, a person-time rate scale, cohort eligibility descriptions, and different follow-up windows. These details clarify the intended question and the way the outcome was defined.
The record does not report the observed malignancy rates, event counts, person-time, or confidence intervals. It therefore cannot establish what the observed rates were, how precisely they were estimated, or whether the cohorts differed on this endpoint. The enrollment of 6617 is not a substitute for those outcome data and does not identify cohort-specific analysis sizes.
Even with reported rates, an observational cohort comparison would describe patterns in the studied groups rather than, by itself, establish that a drug caused an outcome. The groups were not randomized and are explicitly described as not like-for-like controls. Their entry periods and follow-up windows differ, and the record does not report adjustment methods that might address differences between cohorts.
The record’s intention-to-treat definition means follow-up was intended to continue to the end of each cohort’s follow-up period regardless of drug discontinuation. It does not tell readers whether follow-up was complete or how missing information was handled. No medical conclusion about treatment effects should be drawn from the cohort definitions alone; the outcome estimates and fuller analytic details are not reported in the registry record.
12. Why This Trial Matters Statistically
This analysis raises an important statistical distinction: a safety-monitoring cohort study can describe event rates during routine follow-up, but its comparisons do not have the same interpretation as randomized treatment comparisons. Cohort membership was determined by drug initiation and timing, and the registry record cautions that the groups are not like-for-like controls. This makes design features and potential differences between groups central to interpretation.
The endpoint is expressed relative to person-time, which is useful when observation duration varies. Here, the Historical Cohort had up to 24 months of follow-up, while the Raltegravir and Concurrent Cohorts had up to 68 months. A rate scale accommodates differing exposure time in its denominator, but does not by itself remove the effects of calendar period, participant characteristics, or differences in clinical practice and outcome ascertainment.
The record also illustrates why an endpoint definition is not a substitute for results. It clearly defines first malignancy occurrence and the rate unit, yet does not report the rates, event counts, person-time, or confidence intervals. Without those estimates, neither the magnitude nor precision of the observed outcome can be assessed. The design and endpoint support understanding of the intended analysis, while the missing results prevent statistical conclusions about the observed pattern.
13. 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 posted record is that it does not report the malignancy rate estimates, event counts, person-time totals, or confidence intervals. The stated enrollment of 6617 does not reveal the cohort-specific analysis populations or the amount of information supporting the endpoint.
The study is observational, with no random allocation stated. The registry record explicitly cautions that the cohorts are not like-for-like controls. The groups are defined by drug initiation and calendar period, and the Historical Cohort’s eligibility period differs from the periods for the Raltegravir and Concurrent Cohorts. Differences in participant characteristics, clinical context, or care over time could affect observed rates; adjustment methods are not reported in the registry record.
Follow-up windows differ across cohorts, with up to 24 months for the Historical Cohort and up to 68 months for the Raltegravir and Concurrent Cohorts. Although the outcome is expressed per person-time, the record does not report follow-up completeness, cohort-specific time at risk, or the approach to deaths and other competing events. It also does not report how malignancy outcomes were identified or adjudicated.
The cohort descriptions are incomplete in the registry record, and further eligibility details are not reported. Statistical analyses, missing-data procedures, multiplicity handling, and the analysis plan are also not reported. These limitations constrain both reproducibility and evaluation of the precision and potential bias of any comparison.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Observational Data Analysis in EuroSIDA (MK-0518-058) — NCT01078233.
- Registry record last updated 2019-11-25; status last verified 2019-11.
- Results first posted 2015-09-17.
- 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.
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17. Record Summary
NCT01078233 is an observational EuroSIDA analysis of health outcomes associated with antiretroviral drugs in people with HIV-1 infection. The registry record lists enrollment of 6617, study start on 2008-05-05, primary completion on 2014-03-06, and status as completed. The sponsor is Merck Sharp & Dohme LLC.
The primary endpoint is first occurrence of any malignancy, including AIDS-defining and non-AIDS-defining malignancy, expressed as events per 100 person-years with a 95% confidence interval. The analysis describes Raltegravir, Historical, and Concurrent Cohorts, with different eligibility periods and follow-up windows. It is not a randomized comparison, and the record states the arms are not like-for-like controls.
The registry record does not report the primary outcome estimates, cohort-specific event counts, person-time, confidence intervals, or statistical analyses. These omissions prevent interpretation of the observed malignancy rates from the registry record alone.