Increasing COVID-19 Testing in Chicago's African American Testing Desserts: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Increasing COVID-19 Testing in Chicago's African American Testing Desserts (NCT05197452), a na na study. The primary outcome is COVID-19 Testing Uptake.

2. Clinical Question

3. Trial Design

The registry describes a completed, single-group study of a community-based approach to increase COVID-19 testing in an underserved African American community in Chicago. The intervention is categorized as behavioral and is described as COVID-19 antigen and PCR testing. The listed allocation is NA, and masking is listed as none. No randomized comparison is described, and the record cautions that the arms are not a like-for-like control comparison.

The enrollment is 2167. The registry start date is 2021-03-23, and the primary completion date is 2022-11-18. The primary outcome timeframe is listed as up to 20 months. Its description says testing uptake was assessed for the period between December 2020 and August 2022, at 397 testing events held at churches or community sites. These are different time descriptions in the registry; their relationship is not explained in the record.

Repeated testing was possible, but the primary measure counted each individual only once. The record describes no pre- and post-evaluations and says the measure was based on a single count. It does not report a concurrent control group, randomization procedures, masking procedures, or a plan for adjusting comparisons. Phase is listed as NA. Further protocol detail, including any planned interim analyses or sample-size justification, is 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: The analysis population included unique individuals tested for Covid-19

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 COVID-19 Testing Uptake, measured over Up to 20 months.

The primary endpoint, COVID-19 Testing Uptake, measures the count of unique neighborhood residents tested for COVID-19 at least once during the stated study period. Its unit is participants. A person who was tested more than once was counted only once, so the measure represents people reached rather than the number of testing visits or tests administered. The posted count is 2167.

A count is useful for describing the number of people who accessed testing through the reported initiative. It does not, on its own, indicate the proportion of the neighborhood that was tested: the record does not report the size of the eligible or resident population as a denominator. Nor does the count show whether uptake increased relative to a prior period or a comparison community. The registry explicitly says that pre- and post-evaluations were not performed and describes the endpoint as a single count of participants tested.

The outcome description places testing events at churches or community sites and defines the population as unique individuals tested. Details on how records were linked to prevent repeat counting, how residency was determined, or how incomplete records were handled are not reported in the registry record. Those details would help readers assess how the count was assembled, but they do not change the stated meaning of the endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a count of participants. In general, a count records how many units meet a defined condition; here, the condition is having been tested for COVID-19 at least once during the specified period. The registry defines the unit as a unique individual, so repeat testing does not increase the primary count. The reported value is 2167.

What does a single-group design allow?

In general, a single-group descriptive study can document what was observed among the group included in the measure. It does not by itself provide the counterfactual needed for a causal comparison: what would have happened to the same population without the initiative. This registry describes no control group and no pre- and post-evaluation. As a result, the posted count can describe participation, but it cannot establish how much testing changed because of the initiative.

Allocation is listed as NA, and the study model is single-group. The record's warning that the arms are not a like-for-like control comparison is consistent with interpreting the outcome as descriptive rather than as a treatment contrast. No adjusted or unadjusted comparative estimate is reported in the registry record.

Why does the unit of analysis matter?

The endpoint counts unique participants, not visits. In general, these are different quantities: counting visits can give more weight to individuals who return, while counting unique people describes how many people were reached at least once. The registry says individuals may have been tested more than once but were only counted once. It also reports 397 testing events at churches or community sites. The event count and participant count therefore describe different aspects of the activity and should not be treated as interchangeable.

The record does not report the total number of residents who could have been reached. Without that denominator, the count cannot be converted into a coverage proportion from the information available in the registry record. No additional rate or percentage is reported for the primary outcome.

How should uncertainty be understood?

In general, a confidence interval describes the range of values reasonably compatible with data under a specified statistical model and assumptions. A hypothesis test evaluates data against a stated null hypothesis under its own assumptions. Neither quantity is reported for this primary count in the registry record. The record also does not describe a statistical model for the endpoint, an uncertainty-estimation procedure, or a hypothesis test. The count is therefore best read as a descriptive result, without an inferential precision estimate attached to it.

Counts can be analyzed with statistical methods when the study question and data structure support that analysis. The appropriate method depends on features such as the source population, how observations were collected, and whether repeated observations are retained. Here, repeat tests were not counted as separate participants for the primary outcome. The registry does not describe a model for repeated testing or any adjustment for clustering by site or event, so such analyses should not be inferred.

What do the planning illustrations represent?

The record describes sample-size illustrations as planning calculations based on an observed effect, not as the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. In general, planning calculations estimate the sample size needed for a future study under specified assumptions. They are not observed power and do not show that the current single-group study had a planned two-arm design.

The registry record does not report the sample-size justification for the study itself. Nor does it report an observed comparative effect for the primary count from which the planning assumptions can be evaluated in context. The planning illustrations should not be interpreted as a retrospective test of whether this study was adequately powered.

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("COVID-19 Testing")
n      <- c(2167)
events <- c(2167)
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  COVID-19 Testing  2167  2167  100.0  99.8  100.0  99.8  100.0  99.8  100.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and zero analysis entries. The primary measure is described as a single count of unique participants tested. The other outcome measures, their definitions, and their results are not reported in the registry record. With no listed analyses, it is not possible to determine which outcomes were tested, whether any analyses were prespecified, or whether multiple statistical comparisons were made.

Multiplicity concerns arise when several hypotheses or outcomes are tested: the chance of at least one false-positive result can increase as the number of tests grows. In general, an analysis plan may address this by specifying a primary hypothesis or adjustment approach. The registry record does not report such a plan or a multiplicity adjustment. Since no primary-outcome test or p-value is reported, multiplicity-adjusted inference cannot be assessed from this record.

The analysis population is described as unique individuals tested for COVID-19. The record does not report the number of people screened or eligible, missing-outcome counts, exclusions, or a method for handling missing data. It also does not report whether the primary count includes every testing record available during the measurement period or how incomplete records were treated. These omissions limit assessment of how representative the counted population is of residents who might have been eligible or approached.

Interim analyses and a detailed statistical analysis plan are not reported in the registry record. The single-group design and lack of pre- and post-evaluation also mean that no change estimate is available for multiplicity procedures to qualify.

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 reports an intervention arm only. For serious adverse events, the at-risk entry is 2167 and the reported event count is 0. For other adverse events, the at-risk entry is 2167 and the reported event count is 0. The deaths entry is also 0. No serious adverse event terms are listed.

These entries describe what was reported in the registry, not proof that no adverse events occurred. The record does not describe how events were monitored, the duration of safety follow-up, how events were attributed, or how missing safety information was handled. The at-risk entries should not be interpreted as an independently verified measure of complete follow-up. With no comparison group, the safety figures do not provide a comparative estimate of risk. They are limited to the reported counts in the intervention arm.

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

The result establishes that the registry reports 2167 unique individuals tested at least once during the period described for testing uptake. It also records 397 testing events at churches or community sites. Because people could be tested more than once but were counted once in the primary measure, the participant count describes reach in terms of individuals rather than visits.

The result does not establish the proportion of the surrounding community reached. The registry does not report a total eligible or resident population to serve as a denominator. Nor does it establish that testing uptake increased: no pre- and post-evaluations were performed, and there is no like-for-like control group. The stated purpose of increasing uptake is not itself evidence of a measured change or a causal effect.

The count also does not indicate infection frequency, test positivity, changes in disease outcomes, or the consequences of testing. Those outcomes are not reported in the registry record. No statistical uncertainty interval or comparative analysis is reported for the primary count. Readers should therefore interpret it as a descriptive measure of the number of people counted as tested, not as a rate, an effect estimate, or evidence about health outcomes.

The absence of reported serious adverse events, other adverse events, and deaths is similarly a description of the registry entries. Without details about monitoring and follow-up, zero reported events cannot establish that events were impossible or that reporting was complete. The record offers useful information about the scale of documented testing activity, while leaving important questions about coverage, change over time, and attribution unanswered.

14. Why This Trial Matters Statistically

This study addresses an important statistical distinction in community health research: documenting activity is not the same as estimating a change in population uptake. A count of unique residents tested can describe the scale of recorded reach. It becomes a measure of coverage only when paired with a suitable population denominator, and it becomes evidence of change only when the design includes an interpretable comparison over time or across groups.

The registry clearly defines the primary measure at the participant level and says repeat testing was counted only once. That distinction helps prevent confusion between people reached and testing events. Reporting both the unique-participant count and the number of church or community-site events gives readers separate information about individuals and activity, although the record does not report a comparative outcome.

The study's setting also makes the distinction between program intent and measurable impact especially important. The stated aim was to increase COVID-19 testing in an underserved African American community in Chicago. The posted result documents testing activity, but the design information does not support estimating how much the initiative changed uptake. Recognizing that limit does not diminish the descriptive value of the count; it clarifies the question the data can answer.

For future evaluations, a clearly defined eligible population, consistent measurement periods, and a prespecified comparison could help distinguish reach from change. Those are general design considerations, not features reported for this study. The registry record does not provide a protocol or statistical plan establishing that such features were intended.

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 is the absence of a comparison that can establish change or attribution. The study is listed as single-group, allocation is NA, and the record says pre- and post-evaluations were not performed. The reported count therefore describes participants tested, not an estimate of the initiative's effect on uptake.

No population denominator is reported, so the count cannot establish what share of residents was reached. Eligibility criteria, recruitment procedures, the number of residents approached, and reasons for non-participation are not reported in the registry record. This limits assessment of how the people tested relate to the broader community the initiative aimed to serve.

The outcome description gives a testing activity period between December 2020 and August 2022, while the registry lists a study start date of 2021-03-23 and a primary completion date of 2022-11-18. The record does not explain how these dates relate to the endpoint's measurement window. It also does not report how repeat participants were identified, how residency was verified, or how incomplete records were handled.

Only the primary measure is described in the registry entries, despite the registry listing three outcome measures. Statistical methods, uncertainty estimates, missing-data procedures, interim analyses, and a sample-size justification are not reported in the registry record. Safety-monitoring details are also absent. These limitations constrain interpretation of both the uptake count and the safety entries.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Increasing COVID-19 Testing in Chicago's African American Testing Desserts — NCT05197452.
• Registry record last updated 2024-05-24; status last verified 2024-05.
• Results first posted 2024-05-24.
• 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

The registry record identifies a completed, single-group study sponsored by Rush University Medical Center. It describes a behavioral intervention involving COVID-19 antigen and PCR testing, with testing available at churches or community sites in a highly segregated and underserved African American community in Chicago. The registry start date is 2021-03-23, and the primary completion date is 2022-11-18.

The primary outcome is a count of unique participants tested at least once. The registry reports 2167 participants and notes 397 testing events during the period between December 2020 and August 2022. Repeat testing was possible but did not add to the unique-participant count. No pre- and post-evaluations or like-for-like control comparison are described. The record lists three outcome measures and zero analysis entries; details beyond the primary outcome are not reported in the registry record.