Screening for HPV and Cervical Cancer in Young Women With Perinatally Acquired HIV: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Screening for HPV and Cervical Cancer in Young Women With Perinatally Acquired HIV (NCT04587050), a registered phase not stated study. The primary outcome is Prevalence of Abnormal Cervical Cytology.

2. Clinical Question

The study concerns cervical and HPV screening in women with perinatally acquired HIV. Its primary question is how many cervical samples from sexually active participants had abnormal cytology. The record describes a cross-sectional, observational study rather than a trial comparing assigned treatments. It also describes an investigation of high-risk HPV status and HPV vaccine uptake and response.

The record lists high-risk HPV prevalence by subtype, CIN2+ prevalence, and HPV serology for types 16/18 among the secondary outcomes. Those measures address HPV infection, cervical changes, and serological status; they are not substitutes for the primary cytology count. The record does not report numerical outcome results, so it cannot establish the observed prevalence of abnormal cytology or the secondary outcomes.

3. Trial Design

This was a cross-sectional, observational study, not a randomized clinical trial. Its stated focus was high-risk HPV status, cervical cytology, and HPV vaccine uptake and response in young women with perinatally acquired HIV. Imperial College London is listed as the sponsor. The study status is completed, with a start date of 2021-07-19 and a primary completion date of 2023-06-30. Enrollment is listed as 57.

The registry record describes two cohorts. Cohort 1 comprised women with perinatally acquired HIV aged 18 or over who were sexually active. Cohort 2 comprised women with perinatally acquired HIV aged 18 or over who were not sexually active. The record does not state how participants were allocated to cohorts. Because cohort membership reflects sexual activity, and because the primary outcome was not measured in cohort 2, these cohorts should not be read as treatment and control arms or as directly comparable groups.

The listed procedures were human papillomavirus testing, cervical cytology, and HPV serology. For the primary cytology outcome, a cervical sample was taken in the clinic setting and sent to a laboratory for examination. The registry record states that no women in cohort 2 were analysed for this outcome because they were not sexually active and a cervical sample was not taken as per the protocol.

The primary outcome timeframe is listed as 1 year. The record does not explain further how that timeframe relates to sample collection or follow-up. The primary outcome is a participant count, not a reported treatment effect. The record lists 4 outcome measures and 0 analyses, and does not report the primary outcome count or numerical results for the secondary outcomes. It also does not report a statistical analysis plan or details of how the observed data were analysed.

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: Opportunistic recruitment

Overall Study

Analysis population for the primary outcome, as defined in the registry: Zero women analysed in cohort 2 as these women were not sexually active and so cervical sample was not taken as per the protocol

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 Prevalence of Abnormal Cervical Cytology, measured over 1 year.

The primary endpoint is the prevalence of abnormal cervical cytology, defined in the registry record as the number of samples with a non-normal cytology result out of the total number tested. The description gives dyskaryotic cells as an example of a non-normal result. The endpoint is reported in participants and is a count of participants with an event, rather than a continuous measurement.

Cytology examines cells from a cervical sample. In general, classifying a result as normal or abnormal gives a screening measure that can describe how often cell changes are found in the population tested. The count needs to be interpreted alongside the number of participants who were tested: a count alone does not convey the proportion of tested participants with an abnormal result. The registry record does not report either the primary count or the total tested, so the prevalence cannot be read from the record.

The endpoint applies to participants who had a cervical sample taken. The record explicitly says that no women in cohort 2 were analysed for the primary endpoint because no cervical sample was taken in that cohort. This is a design-defined absence of measurement for that cohort, not a reported normal cytology result. The primary outcome timeframe is listed as 1 year, but the record does not further describe the timing of sample collection within that timeframe.

Cytology is only one of the study's screening measures. The record separately lists high-risk HPV prevalence by subtype, CIN2+ prevalence, and HPV serology for types 16/18 as secondary outcomes. These outcomes describe different findings and should not be treated as interchangeable with abnormal cytology.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a cross-sectional observational study and defines the primary outcome as a participant count. Those features shape the statistical interpretation. The outcome is a binary classification at the participant level: a tested participant either had a non-normal cytology result or did not. A count of participants with the event can be paired with the count tested to describe prevalence. The record gives the definition but does not report those counts.

What does a prevalence measure describe?

In general, prevalence describes the frequency of a condition or finding in a defined population at the time or within the period assessed. For this endpoint, the relevant population is the participants who had cervical cytology performed. The numerator is the number of tested participants whose result was non-normal, and the denominator is the number tested. A count without its denominator cannot by itself describe the proportion with abnormal cytology. The registry record reports neither count, so no prevalence can be reconstructed from the recorded information.

Prevalence is descriptive. It does not, by itself, show why a finding occurred or whether an exposure caused it. This distinction is particularly important for an observational study: the record does not describe random assignment to interventions. The diagnostic procedures are measurements, not treatment groups. Findings from participants grouped by sexual activity would not establish that sexual activity caused any difference, even if group-specific results were available.

Why does the cohort definition matter?

The cohorts were defined by sexual activity. The record states that women in cohort 2 did not have cervical samples taken and that zero women in that cohort were analysed for the primary endpoint. Thus, the absence of cytology results in cohort 2 is built into the measurement process described in the record. It should not be interpreted as a set of normal results, nor treated as ordinary missing measurements without considering that the test was not taken under the stated protocol.

In general, comparisons are easiest to interpret when groups are eligible for the same measurements and are alike in relevant ways. Here, the record explicitly cautions that the arms are not a like-for-like control comparison and does not state allocation. Even if group counts were reported, comparing the primary cytology outcome across the two cohorts would be inappropriate when that outcome was not measured in cohort 2. The record does not provide a separate comparative analysis.

How should uncertainty be understood?

For a binary outcome, an estimate of prevalence is often accompanied by a confidence interval. In general, an interval reflects sampling uncertainty under specified statistical assumptions. A narrower interval indicates greater precision under those assumptions, while a wider interval indicates less precision. An interval does not account automatically for selection bias, measurement differences, or other systematic limitations. No confidence interval or other uncertainty estimate for the primary outcome is reported in the registry record.

The record does not report whether the cytology classification was assessed consistently across participants, how indeterminate results were handled, or whether all eligible participants were tested. These details can affect how confidently a prevalence estimate represents the intended population. Their absence means the registry description is not enough to assess those aspects of measurement and analysis.

What do the planning assumptions mean?

The registry information describes a planning illustration based on the observed effect, rather than a sample-size justification for the study's own design. Its stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For non-time-to-event outcomes, such illustrations are expressed as participants per arm. Time-to-event illustrations use the total number of events and the Schoenfeld method. These are planning conventions, not observed results and not evidence that the study was designed or conducted with those assumptions.

Because this study is described as observational, the equal-allocation assumption in a planning illustration should not be mistaken for the way participants were assigned. The record does not state allocation, and the cohort sizes listed in the safety summary are not equal. A planning estimate based on an observed effect is also dependent on the effect used as its input. The primary result and effect size are not reported in the registry record, so the magnitude underlying any such illustration cannot be assessed from the registry information stated.

Sample-size planning is not observed power. In general, power is a design-stage probability defined under assumptions about an effect, variability, allocation, and analysis. A planning illustration indicates what sample size might be associated with those assumptions; it does not establish that an observed finding is reliable or that a null finding shows no effect. The registry record does not report its own sample-size justification, and no planning estimate values are stated in the registry information described.

What can be inferred from the analysis listing?

The registry record lists 4 outcome measures and 0 analyses. This distinguishes having outcomes defined from having numerical analyses reported. A defined endpoint does not itself supply a result, and a completed study status does not fill in the unreported outcome counts. No estimate, significance test, confidence interval, adjustment method, or model specification for the primary endpoint is reported in the registry record. Statistical interpretation should therefore remain descriptive about the design and avoid implying a result that is not recorded.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Cohort 1: Women Living With HIV Who Are Sexually A")
n      <- c(46)
events <- c(12)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Cohort 1: Women Living With HIV Who Are Sexually A  46  12  26.1  14.3  41.1  15.6  40.3  15.6  40.3

11. Multiplicity, Missing Data and Analysis Populations

The record lists 4 outcome measures, including abnormal cervical cytology as the primary outcome and secondary outcomes for high-risk HPV by subtype, CIN2+ prevalence, and HPV serology for types 16/18. The study summary also describes HPV vaccine uptake and response as areas of interest. Assessing several outcomes can raise multiplicity concerns: in general, the more statistical tests performed, the greater the chance of at least one apparently notable result arising by chance if tests are interpreted independently. The registry record lists 0 analyses and does not report a multiplicity strategy or adjusted results. It is therefore not possible to determine whether any adjustment was used.

The record does not report a missing-data approach, the number of participants with unavailable outcome data, or an analysis population for the primary result. It does state that no women in cohort 2 were analysed for the primary outcome because those women were not sexually active and a cervical sample was not taken as per the protocol. That is a specified absence of primary endpoint measurement in cohort 2, not a cytology classification. The record does not describe how missing or unusable samples, if any, were handled in cohort 1.

In general, the analysis population defines who contributes to an estimate. For prevalence, the tested participants and the criteria used to include their results should be clear. Since neither the tested denominator nor a primary analysis population is reported, the coverage of the endpoint cannot be assessed. The listed enrollment of 57 should not be treated as the number tested for cytology; the registry record does not state that those figures are the same.

Details such as prespecified analysis procedures, subgroup analyses, and handling of repeated or incomplete measurements are not reported in the registry record. Without those details and the outcome values, readers cannot evaluate the extent to which the stated outcomes were analysed as planned or how multiplicity and missingness may affect the findings.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry safety summary separates the cohorts and reports participants at risk, participants affected by serious events, participants affected by other events, and deaths. For cohort 1, titled Women With HIV Sexually Active, the record lists 54 at risk for serious events and 54 at risk for other events; 0 were affected in either category, and deaths are listed as 0. For cohort 2, titled Women With HIV Not Sexually Active, it lists 3 at risk for serious events and 3 at risk for other events; 0 were affected in either category, and deaths are listed as 0.

These entries describe what the registry safety summary records; they are not a comparison of treatment safety because the study is observational and the cohorts are not like-for-like control groups. The listed counts do not establish that no adverse effects were possible. They should be read as no affected participants recorded in the reported serious and other event fields, within the registry summary.

The record does not list top serious event terms. It does not provide further detail about event definitions, collection procedures, follow-up for safety, or whether all events were captured. The safety figures also do not provide the primary cytology denominator and should not be used to infer how many participants had cervical testing.

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

The record establishes that a completed cross-sectional observational study was designed to examine HPV and cervical screening findings in young women with perinatally acquired HIV. It identifies the cohort definitions, diagnostic procedures, primary outcome, and secondary outcome topics. Those details clarify what the study intended to measure. They do not reveal the prevalence of abnormal cytology or the frequency of the secondary outcomes, because numerical results are not reported in the registry record.

In particular, the primary endpoint is defined as the count of tested participants with a non-normal cervical cytology result. Without that count and the number tested, no prevalence estimate can be interpreted. The listed enrollment cannot stand in for the endpoint denominator. Similarly, naming high-risk HPV, CIN2+, and HPV serology outcomes does not establish their observed values. Results for vaccine uptake and response are not reported in the registry record.

The absence of a primary outcome analysis for cohort 2 is also important. The record says cervical samples were not taken from women in that cohort, so there is no cytology finding to compare with cohort 1. This should not be expressed as a normal outcome, a lower prevalence, or evidence that screening findings differed by sexual activity.

The study does not test the effect of a treatment. The diagnostic tests are ways of measuring outcomes, and the observational cohort structure does not support a causal treatment claim. The registry record itself notes that the arms are not a like-for-like control comparison and does not state allocation. Even when observational estimates are available, they describe measured patterns in the studied participants and may be influenced by how participants were selected and measured.

What the record does support is a description of the research question and its measurement limits. It does not support conclusions about the magnitude, precision, or direction of any outcome, or about whether screening findings were more or less common in either cohort. Such conclusions require numerical results and analysis details not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a clearly stated outcome and an outcome result. The primary endpoint is defined in interpretable terms: participants with non-normal cytology among participants tested. Yet the registry record lists 0 analyses and does not report the count or denominator. This makes the limits of registry interpretation especially clear: a precise endpoint definition cannot substitute for numerical findings.

The cohort structure highlights a second important issue. The groups are based on sexual activity, but the primary measurement was not made in cohort 2. A comparison requires outcome information on the groups being compared; when one group was not measured for the endpoint, a direct comparison is unavailable. Treating the unmeasured cohort as having normal cytology would confuse absence of measurement with a negative finding.

The record also illustrates why observational cohorts should not automatically be interpreted as treatment and control arms. No treatment assignment is described, allocation is not stated, and the registry warns that the cohorts are not like-for-like. Statistical methods cannot remove that basic design distinction or create a causal contrast from groups that were not assigned to interventions.

Finally, the record names multiple outcome areas, including cytology, high-risk HPV, CIN2+, and serology. In general, multiple outcomes require careful interpretation and transparent reporting of analysis choices. The record lists 0 analyses and does not state how multiplicity was handled. These limitations do not erase the value of the research question, but they determine what can be concluded from the registry record: the design and intended measurements are described, while the outcomes and their precision are not.

15. 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 statistical interpretation is that the registry record does not report the primary cytology count, the number tested, or a prevalence estimate. It lists 0 analyses, so no primary effect estimate, uncertainty interval, or test result is available. Numerical findings for the listed secondary outcomes are also not reported in the registry record. The completed status and enrollment listing do not resolve these omissions.

The primary endpoint was not measured in cohort 2. The record attributes this to the protocol: women in that cohort were not sexually active and no cervical sample was taken. As a result, the primary cytology outcome cannot be compared across the cohorts. Any description of the outcome must be limited to the participants tested, whose number is not reported.

The study is cross-sectional and observational. It does not describe treatment assignment, and allocation is not stated. The cohorts are defined by sexual activity and are explicitly not described as a like-for-like control comparison. These design features limit causal interpretation and make an unadjusted comparison between cohorts unsuitable as a treatment effect.

Other analysis details are not reported in the registry record, including the statistical analysis plan, missing-data handling, outcome-specific analysis populations, and multiplicity procedures. The record also does not provide further detail about how cytology results were classified beyond the stated example of dyskaryotic cells. These omissions limit assessment of measurement consistency, selection, and analytic choices. The safety summary reports zero affected participants in the listed event categories, but does not give further event-collection details or top serious event terms.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Screening for HPV and Cervical Cancer in Young Women With Perinatally Acquired HIV — NCT04587050.
• Registry record last updated 2024-12-10; status last verified 2024-12.
• Results first posted 2024-12-10.
• 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.

19. Record Summary

NCT04587050, titled Screening for HPV and Cervical Cancer in Young Women With Perinatally Acquired HIV, is a completed cross-sectional observational study sponsored by Imperial College London. The registry lists enrollment of 57, a start date of 2021-07-19, and a primary completion date of 2023-06-30.

The study describes sexually active and not sexually active cohorts of women with perinatally acquired HIV aged 18 or over. Its primary outcome is the count of participants with abnormal cervical cytology among those tested, with a timeframe of 1 year. The record states that no women in cohort 2 were analysed for this outcome because no cervical sample was taken in that cohort.

High-risk HPV prevalence by subtype, CIN2+ prevalence, and HPV serology for types 16/18 are listed as secondary outcomes. The registry record lists 4 outcome measures and 0 analyses. It does not report numerical primary or secondary outcome results.