Improving HIV Diagnosis, Linkage to Care, and Prevention Services With HIV Point-of-Care Nucleic Acid Tests: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving HIV Diagnosis, Linkage to Care, and Prevention Services With HIV Point-of-Care Nucleic Acid Tests (NCT04880200), a randomized na study. The primary outcome is Achievement of Viral Suppression.

2. Clinical Question

3. Trial Design

The registry identifies this study as NCT04880200, titled Improving HIV Diagnosis, Linkage to Care, and Prevention Services With HIV Point-of-Care Nucleic Acid Tests. It lists the University of Washington as sponsor, an enrollment of 194, and a completed status. The recorded start date is 2022-03-01 and the primary completion date is 2025-12-23. The phase is listed as not applicable.

The allocation is recorded as randomized, masking as none, and the design model as single-group. The record also describes Standard of Care and POC NAT arms and reports a comparison between them. These design labels and the two-arm outcome reporting do not align neatly; the registry record does not explain the reason. The results for the primary outcome include 31 participants in Standard of Care and 32 in POC NAT, drawn from the population with detectable viral load at baseline.

The intervention description says that participants in the POC NAT & Adherence Intervention arm receive a point-of-care test, with the result conveyed to a provider who delivers the result and an adherence intervention. The comparison arm receives clinical standard of care. The primary outcome is achievement of viral suppression, defined in the record as an undetectable viral load during 1 year of follow-up.

The broader study summary describes several aims, including evaluation of diagnostic performance, PrEP outcomes, time to HIV continuum-of-care outcomes, a behavioral intervention, implementation, and comparisons of multiple point-of-care tests. Those aims provide context, but the posted primary outcome addressed in this analysis is viral suppression. The registry record does not report the original protocol’s detailed allocation procedures or the rationale for the design labels.

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: Participants with detectable viral load at baseline (study visit).

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 Achievement of Viral Suppression, measured over 1 year.

The primary endpoint counts participants who achieved an undetectable viral load during 1 year of follow-up. Its stated population is participants whose viral load was detectable at the baseline study visit. The endpoint is therefore a binary participant-level outcome: each participant either met the stated criterion during the follow-up period or did not. The registry describes the measure as a count of participants, not as a continuous change in viral load.

Viral suppression is used in this study as an outcome relevant to the HIV continuum of care and to the behavioral intervention aim described in the study summary. Restricting the primary endpoint population to participants with detectable viral load at baseline makes the outcome meaningful for assessing whether participants in that population subsequently reached the stated undetectable status. The registry does not provide further operational detail about how viral load was measured, the threshold defining undetectable, or how repeated measurements during follow-up were handled.

The endpoint is reported at 1 year, with 14 participants achieving it in Standard of Care and 15 in POC NAT. The corresponding group sizes are 31 and 32. These counts describe observed outcomes in the reported groups; they do not, without additional assumptions, establish that the intervention caused any difference. Information about missing follow-up measurements and the analysis population beyond the baseline eligibility description is not reported in the registry record.

7. Results Posted in the Registry

• POC NAT: 46.9% (15/32) versus 45.2% (14/31) on control; risk difference 1.7 percentage points (95% CI -22.9 to 26.3), risk ratio 1.04 (0.61–1.77); unadjusted two-proportion z-test p = 0.891.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a binary outcome: participants either achieved an undetectable viral load during 1 year of follow-up or did not. The registry reports counts of participants achieving the endpoint in each group. For this kind of outcome, analysts may compare absolute differences in the proportion meeting the endpoint, or use relative measures such as risk ratios and odds ratios. The registry posts all three types of comparison for POC NAT versus Standard of Care.

What does a risk difference describe?

A risk difference compares the outcome probability in one group with the outcome probability in another by subtracting one from the other. It is an absolute measure, so it describes the size and direction of the contrast in the outcome scale. The posted risk-difference estimate is 0.017. Its confidence interval runs from -0.229 to 0.263, which includes zero, the value corresponding to no absolute difference. Since the interval extends in both directions, the data do not pin down a single direction or a precise magnitude for the contrast.

How do relative measures differ?

A risk ratio compares the probability of the outcome between groups as a ratio. An odds ratio compares the odds of the outcome, rather than the probability itself. The registry reports a risk ratio of 1.038, with a confidence interval from 0.608 to 1.773, and an odds ratio of 1.071, with a confidence interval from 0.398 to 2.887. For either relative measure, a value of one corresponds to no relative contrast. The posted intervals include that reference value. The odds ratio and risk ratio are not interchangeable, especially when an outcome is common; their interpretation depends on which measure is being reported.

What does the p-value say?

The posted p-value is 0.891. In general, a p-value describes how compatible the observed data are with a specified null model, conditional on the statistical assumptions used. It is not the probability that the null model is true, and it does not measure the size or importance of an effect. The registry does not report the test specification or a full statistical analysis plan, so the exact assumptions behind this p-value are not available. The estimate and its interval are important alongside the p-value because they show the range of contrasts that remain compatible with the posted data.

Why do confidence intervals matter?

In general, a confidence interval conveys uncertainty around an estimate. A narrow interval indicates greater precision under the method used; a broad interval indicates that the data are compatible with a wider range of values. The interval around the posted risk difference includes negative and positive values, so it does not isolate a direction of difference. The confidence level and interval-construction method are not reported in the registry record. These details matter when evaluating how the interval was calibrated and what assumptions it relies on.

What information is needed to assess the analysis?

The record identifies the outcome population and follow-up timeframe and posts group counts and comparison estimates. It does not report how missing follow-up data were handled, whether participants were analyzed according to randomized assignment, whether adjustments were made for baseline variables, or how the statistical test was selected. The record also lists randomized allocation, no masking, and a single-group model, while reporting two groups. The basis for those design labels is not described. Without those details, the estimates can be described, but the analysis cannot be fully reconstructed or independently assessed from the registry record alone.

In general, a two-group comparison can be affected by chance variation, missing data, departures from the planned analysis, or differences in the groups at baseline. Random allocation is intended to support comparable groups, but the presence of a randomized label does not substitute for the details of implementation and analysis. The registry record does not report enough information to determine how these issues were addressed for this endpoint.

10. Confidence Intervals and Precision

The point estimate for the risk difference is 0.017. Its confidence interval extends from -0.229 to 0.263, a broad span that crosses zero. In general, an interval crossing zero for an absolute difference means the data are compatible with a contrast favoring either group as well as no difference. Here, the lower and upper bounds include both negative and positive differences, so the direction is uncertain and the magnitude is not tightly estimated.

The relative estimates show similar uncertainty. The risk ratio is 1.038, with a confidence interval from 0.608 to 1.773; the odds ratio is 1.071, with a confidence interval from 0.398 to 2.887. Both intervals include one, the no-relative-difference reference value, and span a range of possible relative contrasts. The registry does not report the confidence level or the method used to calculate these intervals. Their precision should therefore be interpreted from the posted ranges, without assuming undocumented methods.

The comparison is based on 31 participants in Standard of Care and 32 in POC NAT for the primary endpoint population. These group sizes provide context for the uncertainty: the estimated contrast rests on a limited number of observed participants and endpoint events. The overall enrollment of 194 should not be confused with the group sizes for this endpoint; the primary outcome applies to participants with detectable viral load at baseline.

Precision is distinct from whether a result is statistically significant. A point estimate close to zero does not establish equivalence, and a confidence interval that includes zero does not show that no effect exists. Instead, the interval communicates that the posted data do not determine the direction and size of the contrast with high precision. The registry record does not report a prespecified clinically important difference against which to judge the range.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on the observed effect, not the original trial design. The registry record does not report the original sample-size justification or the assumptions used to plan enrollment. For this binary outcome, the figures are participants per arm, not total events. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; each scenario uses a stated fraction of the observed effect.

For planning for 100% of the observed effect, the estimates are 13,278 participants per arm for 80% power and 17,774 participants per arm for 90% power. For planning for 75% of the observed effect, they are 23,588 and 31,578 participants per arm, respectively. For planning for 50% of the observed effect, they are 53,035 and 70,999 participants per arm, respectively.

In plain language, the 80% power column gives the estimated number of participants per arm for a study designed to have an 80% chance of detecting the specified effect under the planning assumptions, if that effect is the true one. The 90% power column gives the corresponding estimate for a 90% chance. Smaller effects require more participants because they are harder to distinguish from random variation. These estimates are not observed power and should not be read as the number actually enrolled or as evidence that the trial was adequately or inadequately powered.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.452; treatment proportion p₁ = 0.469; average p̄ = 0.460.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7049 = 1.3815.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.7048 = 0.5931.
4. n = (1.3815 + 0.5931)² / (0.0171)² = 13,277.0, rounded up to 13,278 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.451612903225806                          # control proportion
p1 <- 0.46875                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(4880200)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 13,278 (80% power), 17,774 (90% power)
 75% of observed effect: n per arm = 23,588 (80% power), 31,578 (90% power)
 50% of observed effect: n per arm = 53,035 (80% power), 70,999 (90% power)
power.prop.test: 13277 
Simulated power at n = 13,278 per arm: 0.800 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The study summary describes multiple aims, including diagnostic accuracy, PrEP uptake and persistence, time to HIV continuum-of-care outcomes, time to virologic suppression, implementation feasibility and acceptability, costs, and comparisons among multiple point-of-care nucleic acid tests. The posted primary outcome is achievement of viral suppression. No secondary outcome measures are posted in the registry record.

When a study examines multiple outcomes, subgroups, timepoints, or comparisons, the chance of at least one apparently unusual result can increase if each is tested separately. In general, multiplicity methods can adjust statistical interpretation or testing thresholds, but the registry record does not report whether any adjustment was planned or used. It also does not identify a hierarchy among the broader study aims beyond naming the primary outcome. The posted p-value should therefore not be assumed to account for all comparisons across the study.

The record includes an outcome comparison and associated estimates but lists no separate analysis records. It does not report a detailed statistical analysis plan, prespecified hypotheses beyond the primary outcome description, or the method used for the posted p-value and intervals. The record also does not state whether analyses were adjusted for baseline covariates or whether analyses of multiple aims were conducted outside the posted results.

Missing-data procedures are not reported in the registry record. There is no description of follow-up completion, how participants without a recorded viral-load result were treated, whether imputation was used, or what sensitivity analyses were performed. The record likewise does not provide analysis-population definitions such as intention-to-treat or per-protocol criteria. These omissions make it difficult to assess the possible influence of missing outcomes or deviations from assigned groups.

The registry labels allocation as randomized but does not describe the randomization process, concealment, or analysis according to assignment. It records no masking. These details are relevant to interpreting the comparison but cannot be inferred from the design label alone. The scope and handling of multiplicity, missingness, and analysis populations therefore remain uncertain from the registry record.

14. 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 1% reporting threshold.

The serious adverse event figures list 97 participants at risk in the POC NAT & Adherence Intervention group and 97 at risk in Standard of Care. The record lists zero participants affected by serious adverse events in each group, zero affected by other adverse events in each group, and zero deaths in each group. No leading serious-event terms are listed.

These are the figures reported for the safety groups; they should be read as registry counts, not as proof that no adverse events occurred outside the recorded categories or reporting period. The record does not describe how adverse events were collected, how long safety follow-up lasted, or whether the groups used for safety reporting match the primary endpoint population. The safety group counts differ from the primary endpoint group sizes, and the registry does not explain the relationship between those populations.

Zero recorded events in the listed categories provides no observed event count to compare between groups, but it does not establish that the interventions are free of risk. Assessment of safety also depends on event definitions, completeness of reporting, follow-up, and the size and characteristics of the population monitored. Those details are not reported in the registry record.

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

The posted result describes a close count of participants achieving an undetectable viral load during 1 year of follow-up: 14 of 31 in Standard of Care and 15 of 32 in POC NAT. The risk-difference estimate is 0.017, and its confidence interval extends from -0.229 to 0.263. The reported p-value is 0.891. Together, these values indicate that the observed group contrast is uncertain and imprecise; the interval includes values favoring either group as well as no difference.

This result does not establish that POC NAT and Standard of Care are equivalent. Equivalence requires a prespecified margin and an analysis designed to assess whether the plausible difference is contained within that margin; neither is reported in the registry record. Nor does the result prove that one approach is superior. The posted estimate is a comparison in the endpoint population and should not be interpreted as a causal effect without considering the trial conduct, analysis methods, and missing-data procedures, which are not fully described.

The result also does not answer all of the study’s broader questions. The study summary describes diagnostic performance, PrEP outcomes, linkage to care, implementation, cost-related work, and comparisons of multiple tests. The registry does not post secondary outcome measures for those aims in this record. The primary viral-suppression comparison cannot be substituted for findings on those other outcomes.

Finally, the primary outcome population is participants with detectable viral load at baseline, whereas the overall enrollment is 194. The endpoint comparison reports 31 participants in Standard of Care and 32 in POC NAT. The registry does not explain the participant flow or the analysis-population rules behind those counts. The result therefore characterizes the posted comparison, not necessarily every enrolled participant or every aspect of the study intervention.

16. Why This Trial Matters Statistically

This trial’s primary result illustrates why an estimate should be read together with its uncertainty. The observed endpoint counts are similar, but the confidence interval for the risk difference is wide and crosses zero. The statistical question is not only whether a point estimate favors one group; it is also how many different underlying contrasts remain compatible with the data. In this record, the possible range is broad enough that the direction and magnitude are not precisely determined.

The study also connects a diagnostic technology with follow-up care. The intervention description includes testing, communication of the result to a provider, and an adherence intervention. The primary endpoint is achievement of an undetectable viral load during 1 year among participants whose viral load was detectable at baseline. This makes clear that the reported endpoint concerns a care-related outcome, not simply whether a point-of-care test produced a result. The broad study summary describes additional diagnostic and implementation questions, but those outcomes are not posted as secondary results in the registry record.

Statistically, this record underscores the importance of distinguishing overall enrollment from the population included in a specific endpoint, and of distinguishing a non-significant comparison from evidence of equivalence. It also shows why readers need information about analysis plans, missing data, outcome definitions, and multiplicity to evaluate results fully. Several of these details are not reported in the registry record.

The posted estimates allow a clear description of the primary comparison, while their uncertainty and the limits of the record constrain what can be concluded. That separation between observed data, precision, and broader interpretation is central to responsible reading of clinical trial results.

17. 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 comparison is based on 31 participants in Standard of Care and 32 in POC NAT, within a population defined by detectable viral load at baseline. The registry does not describe how these participants were selected from the overall enrollment of 194 or provide a flow of participants through follow-up. The relationship between the primary endpoint population and the safety populations is also not explained.

Important endpoint details are not reported in the registry record, including the viral-load threshold defining undetectable, measurement procedures, and handling of repeat measurements. The record does not describe missing outcome data, follow-up completeness, imputation, or sensitivity analyses. It also does not state whether the analysis followed randomized assignment, whether baseline adjustment was performed, or what test produced the posted p-value.

The design description records randomized allocation, no masking, and a single-group model, while also giving two arms and a between-group comparison. The registry does not explain this combination of labels. Allocation procedures and concealment are not described. These gaps limit assessment of how the comparison was implemented and analyzed.

The study summary describes multiple aims, but no secondary outcome measures are posted. The registry does not report a multiplicity strategy, the original sample-size justification, or the confidence level and construction method for the intervals. The planning sample sizes are illustrations based on the observed effect, not the study’s documented design assumptions. Consequently, the posted primary comparison can be described, but its full analytical context and the results of the wider research program are not available in this record.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Improving HIV Diagnosis, Linkage to Care, and Prevention Services With HIV Point-of-Care Nucleic Acid Tests — NCT04880200.
• Registry record last updated 2026-09-17; status last verified 2026-03.
• Results first posted 2026-09-17.
• 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.

21. Record Summary

NCT04880200 is a completed study sponsored by the University of Washington, with recorded enrollment of 194. It concerns point-of-care nucleic acid testing for HIV diagnosis, linkage to care, and prevention services. The primary outcome is achievement of an undetectable viral load during 1 year among participants with detectable viral load at baseline.

The registry reports 14 of 31 participants achieving the endpoint in Standard of Care and 15 of 32 in POC NAT. The risk-difference estimate is 0.017, with a confidence interval from -0.229 to 0.263, and the posted p-value is 0.891. These estimates are imprecise and compatible with contrasts in either direction. The record does not report secondary outcome measures, detailed analysis methods, missing-data procedures, or the original sample-size rationale.