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 Simplification From Tenofovir Plus Lamivudine or Emtricitabine Plus Ritonavir-Boosted-Protease Inhibitor to Ritonavir-Boosted-Atazanavir Plus Lamivudine in Virologically-Suppressed-HIVInfected Adults With Osteopenia (NCT02652793), a na na study. The primary outcome is Change in Bone Mineral Density (BMD) at Lumbar Spine and Left Hip From Baseline to Week 48.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02652793 |
| Phase | NA |
| Condition | Human Immunodeficiency Virus |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 31 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Judit Pich |
| Results posted | Yes |
2. Clinical Question
Population
Adults with HIV who had achieved complete virological suppression for more than 24 weeks, with HIV-1 RNA <50 c/ml, and hip or spine T-scores described as below -1.0 and above -2.5. The trial description characterizes the participants as stable and chronically infected.
Intervention
Participants switched their current antiretroviral regimen to boosted atazanavir and lamivudine, taken once daily. The regimen being replaced contained tenofovir plus lamivudine or emtricitabine and a boosted protease inhibitor.
Comparator
There was no concurrent comparison group. This was a single-group, non-comparative trial, so the results cannot provide a like-for-like estimate against participants who continued their existing regimen or received another treatment.
Primary question
What change in bone mineral density occurred from baseline to week 48 at the lumbar spine and left hip after the regimen switch? The registry record identifies this outcome but does not report the numerical changes or their uncertainty.
3. Trial Design
This was a prospective, open-label, non-comparative, single-group trial lasting 48 weeks. The registry lists an enrollment of 31. Participants with stable HIV infection and sustained virological suppression switched from a regimen containing tenofovir and lamivudine or emtricitabine plus a boosted protease inhibitor to boosted atazanavir plus lamivudine once daily. Because there was no concurrent control group, the study describes outcomes after the switch rather than estimating a randomized difference between treatment strategies.
The trial is listed as completed. Its start is recorded as 2015-11 and its primary completion as 2018-11. The phase and allocation are listed as NA, and masking is listed as none. These registry entries describe the recorded design; they do not establish why the study was conducted in this way or how its enrollment target was selected. A sample-size justification is not reported in the registry record.
Study visits were planned at screening, baseline, weeks 4, 12, 24, and 48. The primary outcome is mean change in bone mineral density at the lumbar spine and left hip from baseline to week 48, measured by dual-energy X-ray absorptiometry. Other outcomes listed include virologic failure, adverse effects, bone-turnover markers, estimated glomerular filtration rate, phosphorus, urine glucose, and urine protein. The registry lists 14 outcome measures and 2 analyses, but does not report a full analysis plan or identify how each outcome was handled analytically.
With a single group, changes over time may be described, but they cannot by themselves isolate the effect of switching from other explanations, such as background changes during follow-up or measurement variability. Those limitations apply even if a before-and-after change is statistically distinguishable from no change.
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: Of the 60 individuals screened, 29 were excluded prior to assignment due to normal bone mineral density, prior virological failure, hypogonadism, or contraindicated medications. A total of 31 participants were enrolled and switched to the study regimen.
Overall Study
| Stage | RTV-Boosted-ATV + 3TC |
|---|---|
| STARTED | 31 |
| COMPLETED | 27 |
| NOT COMPLETED | 4 |
Reasons for not completing this period:
| Reason | RTV-Boosted-ATV + 3TC |
|---|---|
| Adverse Event | 1 |
| Lost to Follow-up | 2 |
| Withdrawal by Subject | 1 |
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.
Population: Of the 31 participants enrolled, 1 did not initiate treatment after screening and was excluded from all analyses. Therefore, the baseline and analysis population included 30 participants.
| Characteristic | Unit | RTV-Boosted-ATV + 3TC |
|---|---|---|
| Participants analysed | 30 | |
| Age, Continuous | years | 40 (33 to 47) |
| Sex: Female, Male: Female | Participants | 4 |
| Sex: Female, Male: Male | Participants | 26 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 30 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: Spain | Participants | 30 |
| Bone Mineral Density (BMD) at Baseline by DXA: Lumbar Spine | g/cm² | 0.88 (0.80 to 0.90) |
| Bone Mineral Density (BMD) at Baseline by DXA: Left Hip | g/cm² | 0.72 (0.68 to 0.76) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Bone Mineral Density (BMD) at Lumbar Spine and Left Hip From Baseline to Week 48, measured over Baseline to Week 48.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | g/cm² |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is mean change in bone mineral density, expressed in g/cm², from baseline to week 48 at the lumbar spine (L1-L4) and left hip. The registry specifies measurement by dual-energy X-ray absorptiometry in adults with HIV and hip or spine T-scores in the stated osteopenia range. The endpoint therefore focuses on how a measured skeletal quantity changes over the follow-up period after the regimen switch.
Bone mineral density is a continuous measure. A mean change describes the average direction and magnitude of change across the participants included in the analysis; it does not show whether every participant changed in the same direction. The accompanying standard deviation, when reported, describes how variable individual changes were around the mean. A confidence interval would describe the precision of an estimated mean change, but no numerical mean changes, standard deviations, or confidence intervals are reported in the registry record.
Measuring both the lumbar spine and left hip gives information about two anatomical sites, which need not have identical changes. The registry names both locations as part of the primary outcome but does not report the numerical results by site. The endpoint is a measurement outcome, not by itself a direct account of symptoms, fractures, or other clinical events; those outcomes are not identified as the primary endpoint in this record.
In general, repeated measurements can be useful for describing change from an individual’s baseline, while interpretation still depends on measurement precision, the analysis population, and how missing follow-up measurements are handled. Those details are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted registry information defines the central question as change in lumbar-spine and left-hip bone mineral density between baseline and week 48. It does not include numerical estimates of either change, sample sizes for the primary analyses, standard deviations, confidence intervals, or tests of statistical significance. Consequently, the direction, size, and precision of the primary outcome cannot be assessed from the registry record. A numerical treatment effect should not be inferred from the study title or its rationale.
The design also sets a limit on what any before-and-after result could establish. Every participant was assigned to the switch strategy in the single-group design, and there was no concurrent control group. A mean change during follow-up would describe what happened in the analyzed participants after switching, but would not quantify how their bone mineral density would have changed had they continued their previous regimen. Without that comparison, changes cannot be attributed to the switch alone.
The registry records an enrollment of 31, while the serious and other adverse-event risk sets are each listed as 30. The reason for this difference is not reported in the registry record. It is not possible to determine from those counts alone whether the same participants contributed to every outcome, whether any participants lacked follow-up measurements, or how such cases were handled in the primary analysis.
The trial lists additional outcomes relating to virologic failure, adverse effects, bone turnover, and renal measures. Their presence indicates that the study recorded or planned to assess more than the primary endpoint, but does not establish that every outcome has a posted numerical result. The definitions and numerical findings for these measures are not reported in the registry record presented. A complete interpretation would require outcome-specific estimates, denominators, and uncertainty measures.
General statistical interpretation distinguishes the estimated effect from its precision. A confidence interval can indicate a range of values compatible with the data under the analysis assumptions; it does not make an uncontrolled comparison causal. A small or imprecise estimate may leave meaningful changes compatible with the data, while a more precise estimate may narrow that uncertainty. Because the registry record does not report the primary estimate or its interval, neither precision nor statistical compatibility with particular values can be evaluated.
The listed planning illustration uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with an effect defined as a stated fraction of the observed effect. It is explicitly a planning exercise rather than the study’s design. The trial itself was single-group, and the numerical planning outputs and observed effect values are not reported in the registry record. Such illustrations are not observed power and should not be read as evidence about the trial’s results.
9. Statistical Methods Explained
The primary outcome is continuous: bone mineral density is measured in g/cm², and the stated summary is a mean. For a continuous measure, a mean change can describe the average within-person difference between follow-up and baseline among the analyzed participants. The registry identifies baseline to week 48 as the timeframe and standard deviation as the measure of dispersion. The numerical summaries needed to interpret that endpoint are not reported in the registry record.
What does a mean change describe?
In general, a mean change combines the individual changes into one average. It can be informative about the overall direction of the data, but it may conceal variation: some participants can have increases, some decreases, and some little measured change while the average remains similar. A standard deviation conveys how spread out observations are around the mean. It is not the same as the uncertainty in the estimated mean. A confidence interval, if reported, would communicate uncertainty around the estimate under the model and analysis assumptions. No confidence interval or numerical standard deviation for the primary outcome is reported in the registry record.
The outcome is specified at two sites, the lumbar spine (L1-L4) and left hip. These are separate measurements, and their changes should be interpreted separately unless the analysis plan explicitly combines them. The registry record does not provide a rule for combining sites, a hierarchy between them, or a procedure for handling multiple primary comparisons. Those details are not reported in the registry record.
Why does the single-group design matter?
In general, a within-group change compares follow-up measurements with baseline measurements among the same group. It can describe temporal change, but it does not create a counterfactual comparison. A control group could help distinguish changes associated with the intervention from changes that might occur over time for other reasons. This trial is identified as single-group and non-comparative, so it does not offer that direct contrast. Even a precisely estimated mean change would not, by itself, establish that the switch caused the change.
The trial was open label, with masking listed as none. In general, knowledge of treatment assignment may influence behavior, reporting, or decisions about care and assessment. An instrumental measurement such as DXA is not automatically free from all sources of bias; the registry record does not describe assessor masking or other measurement safeguards. It would be inappropriate to assume procedures that are not reported.
How should uncertainty be read?
In general, a confidence interval combines the estimated effect and its precision. A wider interval indicates greater uncertainty about the size of the underlying effect, while a narrower interval indicates greater precision under the chosen method. An interval does not correct weaknesses in study design, and statistical significance does not by itself establish clinical importance. The primary effect estimate, its interval, and a significance test are not reported in the registry record, so these judgments cannot be made from the available results.
Over-dispersion is a general concern when observed variability is greater than a model assumes. When a model underestimates variability, uncertainty estimates can be too small and intervals or tests can be misleading. This concept is more directly relevant to some count or event models than to a simple mean outcome. The registry record does not identify a model for the primary endpoint or report diagnostics, so there is no basis for saying that over-dispersion was assessed or present.
What is the planning illustration?
The stated planning illustration assumes a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It frames effects as stated fractions of the observed effect. These are planning assumptions, not a description of the single-group trial, which had no two-arm allocation. The numerical sample-size illustrations and the observed effect used to produce them are not reported in the registry record. They should not be read as the trial’s planned enrollment, as a justification for its enrollment, or as observed power. A sample-size calculation is a forward-looking planning tool under assumptions; it does not measure the probability that the completed study detected a true effect.
More broadly, the registry lists 14 outcome measures and 2 analyses. The presence of multiple outcomes raises questions about which outcomes were designated primary, how analyses were selected, and whether multiplicity was considered. The primary endpoint is identified, but a detailed statistical analysis plan, prespecified model, covariate adjustment strategy, and procedures for multiple testing are not reported in the registry record. No specific method should be attributed to the investigators without that information.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies mean change in bone mineral density at the lumbar spine and left hip as the primary outcome, and lists 14 outcome measures overall. It also lists 2 analyses. The record does not explain whether the two anatomical sites were treated as separate primary tests, whether one site had priority, or whether any multiplicity adjustment was planned. The analysis plan for the wider set of outcomes is not reported in the registry record.
In general, testing many outcomes can increase the chance of at least one apparently unusual finding when all outcomes are considered together. Methods for addressing this can include prespecifying a primary outcome, adjusting the significance threshold, or treating secondary findings as exploratory. These methods answer different questions, and no particular approach should be assumed for this trial. A stated significance threshold for the planning illustration does not establish the threshold used for the outcome analyses.
Missing data are also important for a baseline-to-week-48 endpoint. The registry record lists an enrollment of 31 and adverse-event risk sets of 30, but does not report the primary outcome analysis denominator or explain the difference. The number of participants with paired DXA measurements, reasons for missing observations, and method for handling missing outcomes are not reported in the registry record. It is therefore not possible to judge whether the analysis used all enrolled participants, only participants with observed measurements, or another population.
The record does not describe an intention-to-treat population, a per-protocol population, imputation, sensitivity analyses, or interim analyses. Their use or absence should not be inferred. In general, conclusions can depend on which participants are included and how missing measurements are treated, particularly when missingness is related to participants’ outcomes or treatment experience. Without the analysis population and missing-data procedures, the scope and robustness of any primary estimate cannot be evaluated.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| RTV-Boosted-ATV + 3TC | 0 | 30 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| RTV-Boosted-ATV + 3TC | 0 of 30 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| RTV-Boosted-ATV + 3TC | 2 of 30 |
Most frequent non-serious adverse event terms
| Event term | Organ system | RTV-Boosted-ATV + 3TC |
|---|---|---|
| Hyperbilirubinaemia | Hepatobiliary disorders | 2 of 30 |
The serious adverse-event figures list 30 participants at risk and 0 affected in the group labeled RTV-Boosted-ATV + 3TC. The record also lists 0 deaths. These counts describe the registry’s serious-event reporting for that group; they do not establish that no non-serious adverse effects occurred or that every participant completed follow-up without an event.
For other adverse events, the record lists 30 participants at risk and 2 affected. The registry lists adverse effects as a secondary outcome, but the figures do not provide event terms, severity details, timing, or an explanation of whether affected participants had one or multiple events. The top serious-event terms list is empty. An empty term list is not evidence that all adverse-event categories were assessed and found absent; the figures and definitions have to be interpreted according to what the registry actually reports.
The enrollment is listed as 31, while both adverse-event risk sets are 30. The reason for that denominator is not reported in the registry record. Risk-set counts should not be assumed to represent the denominator used for the primary bone-density analysis. These safety counts are descriptive, and the trial has no concurrent comparison group for estimating a comparative safety difference.
In general, a zero count in a small study does not prove that an event cannot occur. The precision of an event rate depends on the number observed and the number followed, as well as the event definition and follow-up completeness. No comparative safety conclusion can be drawn from these figures alone.
12. What the Result Does, and Does Not, Mean
The record describes a prospective switch study among adults with HIV who had sustained virological suppression and osteopenia-related bone-density eligibility criteria. Its primary question concerns mean bone mineral density change at the lumbar spine and left hip from baseline to week 48 after switching to boosted atazanavir plus lamivudine. The numerical primary findings are not reported in the registry record, so the amount and direction of change cannot be characterized from the recorded information.
Even if a before-and-after estimate were available, the single-group, non-comparative design would support a description of change over time rather than a direct estimate of what switching changed relative to continuing another regimen. The absence of a concurrent comparator limits causal interpretation. Open-label conduct and unreported details about analysis populations, missing data, and measurement procedures add further uncertainty about how any estimate should be interpreted.
The safety figures record 0 serious adverse events among 30 at risk, 2 participants affected by other adverse events among 30 at risk, and 0 deaths. These counts are descriptive, not comparative. The registry does not provide enough detail about event terms or follow-up to interpret the counts beyond their stated categories and denominators.
General statistical interpretation separates the observed estimate, its precision, and its causal meaning. An estimate describes the analyzed data; its confidence interval indicates uncertainty under the analysis assumptions; and the design determines how strongly the result can support a causal comparison. Here, the numerical primary estimate and precision measures are not reported, while the design has no control group. Neither a treatment benefit nor a lack of benefit can be concluded from the absence of numerical primary results.
The sample-size material is described as a planning illustration based on an observed effect and assumptions for a two-arm design. It is not the trial’s design and is not observed power. The numerical illustrations and effect values are not reported in the registry record. The study’s own sample-size justification is also not reported. These distinctions matter because planning calculations cannot substitute for outcome estimates or resolve the limitations of a completed single-group study.
13. Why This Trial Matters Statistically
Statistically, this trial illustrates the distinction between measuring change and estimating a treatment contrast. A repeated bone-density measure can describe what happened within a group over time. Without a concurrent comparator, however, the study cannot directly distinguish the change associated with switching from other changes that may occur during follow-up. This is a design limitation, not something that can be repaired by applying a more elaborate statistical test to the same single-group data.
The endpoint also highlights the need to report estimates with their uncertainty. Naming a mean change and standard deviation tells readers what kind of summary was intended, but the registry record does not include the numerical primary results or confidence intervals. Without them, readers cannot evaluate the estimated magnitude, the spread of individual changes, or the precision of the average.
Several reporting questions remain relevant to a complete statistical appraisal: how the two bone-density sites were handled, which participants contributed to the analysis, how missing week-48 measurements were treated, and whether the multiple listed outcomes were addressed in a prespecified way. The registry record does not report these details. Their absence prevents a reader from assessing analysis choices and sensitivity to those choices.
The planning illustration is also instructive because its assumptions describe a hypothetical two-arm comparison, whereas the actual trial was single-group. A planning exercise can help explore how sample size depends on an assumed effect and statistical model, but it does not demonstrate that a completed study had adequate power or that an effect was observed. The numerical planning outputs are not reported in the registry record.
These features make the record useful for understanding the trial question and its design while also showing why transparent outcome estimates, denominators, uncertainty measures, and analysis details are essential for interpretation.
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 most direct limitation for interpreting the primary outcome is that numerical lumbar-spine and left-hip bone-density changes are not reported in the registry record. No standard deviations, confidence intervals, or primary-analysis denominators are included in the information available. As a result, neither the magnitude nor precision of the primary outcome can be assessed.
The study is single-group and non-comparative, so it cannot provide a concurrent estimate against continued treatment or another regimen. This constrains causal attribution even if within-group changes were reported. The study is also open label, with masking listed as none; whether outcome assessors were masked is not reported in the registry record.
The enrollment is 31, while the adverse-event risk sets are 30. The reason for this difference is not reported. The primary analysis population, completeness of follow-up DXA measurements, reasons for missing measurements, and missing-data methods are also not reported in the registry record. These omissions make it difficult to establish who contributed to the primary estimate or how representative an analyzed group would be of all enrolled participants.
The registry lists 14 outcome measures and 2 analyses, but does not report the detailed statistical analysis plan, the treatment of the two bone-density sites, or how multiplicity was considered. A sample-size justification and interim-analysis plan are not reported. Although planning assumptions are described, the numerical illustrations are not reported and do not define the trial’s single-group design.
The serious adverse-event summary lists 0 affected among 30 at risk and 0 deaths, while 2 of 30 are listed as affected by other adverse events. Event terms and additional context are limited, and these descriptive counts have no concurrent comparator. Together, these features call for cautious interpretation and do not support conclusions beyond the recorded design and counts.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Simplification From Tenofovir Plus Lamivudine or Emtricitabine Plus Ritonavir-Boosted-Protease Inhibitor to Ritonavir-Boosted-Atazanavir Plus Lamivudine in Virologically-Suppressed-HIVInfected Adults With Osteopenia — NCT02652793.
- Registry record last updated 2025-07-02; status last verified 2025-06.
- Results first posted 2025-07-02.
- 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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18. Record Summary
NCT02652793 is a completed, prospective, open-label, non-comparative, single-group trial with an enrollment of 31. It examined a switch from a tenofovir-containing regimen with lamivudine or emtricitabine and a boosted protease inhibitor to once-daily boosted atazanavir plus lamivudine in virologically suppressed adults with HIV and osteopenia. The study lasted 48 weeks, with visits planned at screening, baseline, weeks 4, 12, 24, and 48.
The primary outcome was mean change in bone mineral density at the lumbar spine and left hip from baseline to week 48, measured by DXA. Numerical primary results and their uncertainty are not reported in the registry record. Listed safety figures include 0 serious adverse events among 30 at risk, 2 affected by other adverse events among 30 at risk, and 0 deaths. The study has no concurrent control group, and key analysis details about the primary endpoint, missing data, and multiplicity are not reported.