Evaluation of the Implementation and Effectiveness of IPP-HPV: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Implementation and Effectiveness of IPP-HPV (NCT02994290), a non-randomized na study. The primary outcome is HPV Vaccine Receptivity Thematic Interview.

2. Clinical Question

3. Trial Design

This completed study evaluated implementation of the Inpatient Postpartum HPV Immunization Quality Improvement Program at Yale New Haven Hospital. The registry lists an enrollment of 817, a start date of 2017-01, and primary completion on 2021-10-31. The sponsor is Yale University. The study is classified as nonrandomized, with no masking and a single-group model. These design labels matter when interpreting the record: receipt or refusal of an inpatient vaccine dose was not assigned by randomization, and the interview groups should not be treated as randomized arms.

The intervention listings include HPV vaccine, categorized as a drug, and the Inpatient Postpartum HPV Immunization Quality Improvement Program, categorized as behavioral. The stated purpose was to assess implementation and identify potential barriers and facilitators to optimize feasibility and effectiveness. The registry describes interviews with postpartum women who received the inpatient dose and women who declined it, but those groups are interview sampling categories rather than evidence of a controlled comparison.

The primary endpoint is qualitative: the number of themes derived from thematic interviews. The record describes in-person, in-depth interviews using a semi-structured guide based on Consolidated Framework for Implementation Research constructs. Interviews were to occur before discharge; if that was not possible, an interview was planned at the 6-week postpartum visit. The record anticipates thematic saturation with about 8-10 individuals per interview group, while also describing the primary population as a random subsample of participants who completed an interview. How these sampling descriptions were implemented is not reported in the registry record.

Seven outcome measures are listed, including vaccine receipt and provider receptivity and concerns. The record lists no analyses and does not report numerical findings for the primary endpoint. A study-specific statistical analysis plan, sample-size justification, and interim analysis plan are not reported in the registry record.

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

Analysis population for the primary outcome, as defined in the registry: 787 total eligible participants

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: 787 total eligible participants and 30 providers

6. Primary Endpoint

The registry lists the primary outcome as HPV Vaccine Receptivity Thematic Interview, measured over up to 6 weeks postpartum.

The primary endpoint is the number of themes derived from thematic interviews about HPV vaccine receptivity. It is not a clinical event rate or a numerical measure of vaccine effectiveness. Instead, it represents the thematic findings identified after interview transcripts are analyzed. The interviews were intended to capture participants’ perspectives and inform understanding of implementation, including potential barriers and facilitators to the program.

The registry describes a semi-structured interview guide based on Consolidated Framework for Implementation Research constructs. It says a codebook would be developed using deductive, theory-driven constructs from the guide, applied to a subset of transcripts, and used alongside standard analytic methods for qualitative data. The endpoint is therefore tied to both the interview material and the analytic process used to identify and organize recurring themes. In general, qualitative themes can help characterize experiences and implementation issues that a count of vaccine doses alone would not capture.

The endpoint’s timeframe is up to 6 weeks postpartum. Interviews were planned before discharge from the postpartum hospitalization, with an interview at the 6-week postpartum visit if the earlier interview was not possible. The registry does not report the observed number of themes, supporting transcript counts, or a numerical summary of how themes were distributed across participants or interview groups. Those endpoint results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a theme count represent?

In general, thematic analysis is a qualitative approach for organizing interview material into recurring concepts or patterns. A theme count is not equivalent to counting participants with a clinical event, and it does not by itself say how frequently each theme occurred. Its meaning depends on the interview questions, transcript content, coding decisions, and the criteria used to treat material as a distinct theme. The registry describes use of a semi-structured guide based on Consolidated Framework for Implementation Research constructs, deductive constructs from that guide, a codebook applied to a subset of transcripts, and standard qualitative analytic methods.

The primary endpoint is the number of themes derived from thematic interviews. The registry does not report the final count, theme definitions, transcript-level coding results, or how disagreements in coding were handled. Those details are not reported in the registry record. Without the results and fuller analytic documentation, a reader cannot assess the content, prevalence, or stability of the themes from the endpoint description alone.

How should the interview groups be understood?

In general, random allocation is used to make treatment groups more comparable at the start of a study. That design feature is absent: allocation is listed as nonrandomized, masking as none, and the model as single group. The descriptions of women who received or declined an inpatient dose therefore identify interview sampling categories, not randomized study arms. The categories may be useful for describing different perspectives, but any comparison between them is observational and potentially influenced by differences between participants.

The record describes purposive sampling of postpartum women in the two categories until thematic saturation was anticipated with about 8-10 individuals per group. It also describes the primary endpoint population as a random subsample of participants completing thematic interviews. The record does not explain how these sampling approaches fit together, whether the anticipated interview counts were reached, or how many interviews were completed. Those details are not reported in the registry record.

What does the design say about statistical inference?

In general, confidence intervals quantify the uncertainty around an estimated quantity under a specified statistical model. A p-value summarizes how compatible data are with a null hypothesis under the assumptions of a test. Neither is meaningful without a defined estimate or analysis. The registry lists no analyses and does not provide a numerical primary endpoint result, an estimate of a group difference, a confidence interval, or a p-value. These inferential quantities are not reported in the registry record.

For qualitative findings, precision is not generally conveyed by a conventional confidence interval around the number of themes. Analysts instead need enough information about participant selection, interview completion, coding procedures, and theme development for readers to judge the scope and credibility of the findings. A planned stopping point based on thematic saturation is a qualitative sampling rationale; it is not a statistical power calculation. The registry gives an anticipated interview count but does not report whether saturation was reached or how that judgment was made.

What is the role of sample-size planning?

In general, a power calculation is a planning tool for a specified quantitative contrast, assumed effect, significance level, and allocation. It is not evidence that an effect was observed, and it cannot replace reporting the outcome estimate and its uncertainty. The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a fraction of an observed effect. For non-time-to-event outcomes, those calculations are framed as participants per arm; time-to-event planning is framed in total events.

Those assumptions are described as a planning illustration, not the study’s own design. A numerical sample-size justification for the study is not reported in the registry record. No observed effect estimate to support a quantitative planning interpretation is included in the registry record, and no numerical planning estimate is reported in the record. Such illustrations must not be read as observed power or as evidence that the study could detect a particular effect.

How do multiple outcomes affect interpretation?

In general, examining multiple outcomes can increase the chance of highlighting an apparently notable result by chance if many statistical tests are conducted without an appropriate plan. The registry lists seven outcome measures, including vaccine receipt or nonreceipt and provider interview measures concerning receptivity and concerns. It does not list analyses or a multiplicity strategy. A prespecified hierarchy, adjustment approach, or explanation of how findings across outcomes were to be interpreted is not reported in the registry record.

Multiplicity is not limited to formal testing. Qualitative studies may identify many candidate patterns, and the process for selecting, combining, or prioritizing themes can shape the final set. The registry describes a codebook and deductive constructs but does not report the final themes or the full process used to establish them. The statistical and qualitative reporting details needed to assess robustness are therefore not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists seven outcome measures and no analyses. It does not report a multiplicity strategy, such as a prespecified hierarchy among outcomes or an adjustment for testing several quantitative hypotheses. It also does not report which outcomes, if any, were treated as primary for formal statistical testing beyond identifying the thematic interview endpoint as primary. Without reported tests and an analysis plan, the implications of multiple outcomes for inferential error cannot be evaluated from the registry record.

Missing-data handling is not reported in the registry record. The primary endpoint depends on interviews and transcript analysis, yet the number of participants invited, completing interviews, or included in the final analysis is not reported. The record does not state how incomplete interviews, unavailable transcripts, or missing responses would be handled. It also does not describe an imputation method or a sensitivity analysis for missing information.

The analysis population is not fully specified. The primary outcome description refers to a random subsample of overall participants who completed a thematic interview, while the arm descriptions describe purposive sampling of women who received or declined the inpatient dose. How those sampling descriptions were reconciled, and how participants were assigned to analytic groups, is not reported in the registry record. No intention-to-treat or other analysis population is described.

These omissions matter because participant selection and interview completion can affect which perspectives are represented. A thematic analysis of completed interviews describes the material that was collected and analyzed; it cannot automatically represent all enrolled participants. The registry does not report enough information to assess the extent or direction of selection and missingness.

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

The record documents a completed quality-improvement study focused on implementation of inpatient postpartum HPV immunization at Yale New Haven Hospital. It describes a primary qualitative endpoint based on interview themes, a nonrandomized single-group design, and interview categories for women who received or declined the inpatient dose. These details clarify the study’s purpose and the kind of evidence it was designed to collect.

The record does not report the number or content of themes, a numerical vaccine uptake result, or a comparative estimate between women who received and declined a dose. It therefore cannot establish how frequently particular concerns arose, whether perspectives differed between the interview categories, or how the program changed vaccination. A comparison between self-selected recipients and decliners would not, in any case, be equivalent to a randomized treatment comparison.

In general, implementation interviews can describe experiences and identify issues that may inform program development. They do not alone quantify causal effects on uptake or clinical outcomes. Likewise, a count of themes does not indicate how many people expressed each theme unless those participant-level results are reported. The registry’s endpoint definition is not a substitute for its outcome findings.

The record also does not provide enough adverse-event information to estimate risk among participants who received vaccine: the listed eligible group has zero participants at risk and zero affected, and no serious-event terms are listed. This is not a denominator-based safety analysis. Numerical outcome findings, a detailed account of missing interviews, and the analysis methods used for results are not reported in the registry record.

12. Why This Trial Matters Statistically

This study is statistically important because it illustrates how the design and endpoint should guide interpretation. The primary question is framed around implementation and qualitative themes, while the study is nonrandomized and described as single group. Treating interview categories as randomized arms or interpreting the endpoint as a conventional clinical outcome would misrepresent the evidence the registry describes.

It also highlights the importance of reporting the path from enrollment to analysis. The record lists 817 enrolled participants but does not report how many completed interviews or contributed to the primary endpoint. Its description includes both a random subsample of interview completers and purposive selection of vaccine recipients and decliners. Reporting how those approaches were implemented would help readers judge whose experiences informed the themes and how far those findings might apply.

For qualitative outcomes, transparent methods are central to evaluating the result: how transcripts were coded, how themes were distinguished, and how the analytic team judged that the themes captured the material. The registry describes some intended procedures, including a codebook and theory-driven constructs, but does not report the resulting themes or enough detail to evaluate the completed analysis.

Finally, the absence of numerical analyses and outcome findings means statistical uncertainty cannot be assessed. Sample-size illustrations are planning tools, not observed power or evidence of an effect. The distinction between a study’s implementation aim, its qualitative endpoint, and any quantitative comparison is essential to understanding what the registry record can support.

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 available registry information has important limitations for evaluating this study’s findings. Most importantly, numerical results for the primary endpoint are not reported in the registry record. The record gives the endpoint definition and planned interview approach, but not the number of themes, theme descriptions, or participant-level patterns. It also lists no analyses, so estimates, uncertainty intervals, and statistical tests cannot be assessed.

The study is nonrandomized, has no masking, and is classified as single group. The groups described for interviews are based on receipt or refusal of the inpatient dose, so they are not comparable by design in the way randomized groups would be. Factors associated with accepting or declining vaccination, and any adjustment for such factors, are not reported in the registry record.

Sampling information is incomplete and appears in two forms: the primary population is described as a random subsample of participants who completed interviews, while the arm descriptions refer to purposive selection of recipients and decliners. The record does not report how these descriptions relate to actual recruitment, the final number interviewed, whether anticipated thematic saturation was reached, or how many transcripts entered analysis. These details limit assessment of selection and representativeness.

The registry lists seven outcome measures but does not report a multiplicity plan, missing-data approach, or analysis population. It also gives adverse-event entries with zero participants at risk, which cannot support an event-rate assessment. A study-specific sample-size justification and interim analysis plan are not reported in the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Evaluation of the Implementation and Effectiveness of IPP-HPV — NCT02994290.
• Registry record last updated 2023-01-09; status last verified 2022-12.
• Results first posted 2023-01-09.
• 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.

17. Record Summary

The registry record describes the completed Evaluation of the Implementation and Effectiveness of IPP-HPV, sponsored by Yale University. Enrollment was 817; the study started in 2017-01 and reached primary completion on 2021-10-31. It is classified as nonrandomized, unmasked, and single group.

The program focused on inpatient postpartum HPV immunization at Yale New Haven Hospital. Its primary endpoint is the number of themes derived from HPV vaccine receptivity interviews, planned before discharge or at the 6-week postpartum visit. The record describes interview groups of women who received or declined an inpatient dose and anticipates thematic saturation with about 8-10 individuals per group.

Seven outcome measures are listed. Numerical primary results, analyses, and the final interview and transcript counts are not reported in the registry record. The record does not provide a study-specific statistical analysis plan or sample-size justification.