DELTA Trial: Does Embolization With Larger Coils Lead to Better Treatment of Aneurysms Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for DELTA Trial: Does Embolization With Larger Coils Lead to Better Treatment of Aneurysms Trial (NCT01943591), a randomized na study. The primary outcome is Major Recurrence of Lesion or Presence of Residual Aneurysm.

2. Clinical Question

The question is about a radiographic outcome after coiling, rather than a direct comparison of symptoms or daily functioning. The registry also lists packing density, serious procedural adverse events, and modified Rankin Score above 2 as secondary outcomes. These outcomes address related but distinct aspects of the treatment: the degree of aneurysm filling, safety events, and a measure of disability.

The trial’s stated rationale was that larger bare platinum coils might increase packing density and thereby reduce remnants or recurrences. That is the hypothesis motivating the comparison, not a result established by the rationale itself. The posted primary results describe the number of participants meeting the combined radiographic endpoint; they do not, on their own, establish the mechanism behind any difference between coil sizes.

3. Trial Design

DELTA was a randomized, parallel-group trial with single masking. The registry lists an enrollment of 210 and a completed status. The study start date is 2013-11-13, and the primary completion date is 2018-12-05. The sponsor was Centre hospitalier de l'Université de Montréal (CHUM). The phase is listed as NA.

Participants were assigned to endovascular coiling with 15-caliber platinum coils or standard 10-caliber coils. The registry describes the 15-caliber arm as endovascular embolization coiling using 15-caliber platinum coils and the comparator as endovascular embolization coiling using standard 10-caliber coils. The identity of the party or parties masked is not reported in the registry record.

The primary outcome was assessed at 1 year and defined as major radiographic recurrence of the lesion or the presence of a residual aneurysm, judged by a core lab. The posted primary outcome counts are 26 among 104 participants in the 15-caliber group and 20 among 106 in the 10-caliber group. The outcome population is not described further in the registry record.

The registry also lists packing density, procedural serious adverse events, and modified Rankin Score above 2 among the secondary outcomes. Packing density was assessed within the first 3 days after coiling, while modified Rankin Score was assessed at 1 year follow-up. The original sample-size justification, eligibility criteria beyond the aneurysm description in the summary, and details of the masking procedure 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

Reasons for not completing this period:

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 Major Recurrence of Lesion or Presence of Residual Aneurysm, measured over 1 year.

The primary endpoint combines two radiographic findings: major recurrence of the aneurysm lesion and the presence of a residual aneurysm. A core lab judged whether the imaging finding met the endpoint definition. The registry reports the outcome as a count of participants, with a 1-year timeframe.

A combined endpoint can capture more than one form of an incomplete or less durable radiographic result. This is relevant to the trial’s stated question because the investigators were interested in whether coil caliber could affect remnants or recurrence. Combining the findings also means the reported count does not distinguish how many participants had recurrence versus a residual aneurysm; that component-level breakdown is not reported in the registry record.

Radiographic outcomes provide information about the appearance of the treated aneurysm, but they are not interchangeable with functional or safety outcomes. A radiographic finding does not by itself describe symptoms, disability, the need for retreatment, or later clinical events. Those issues require their own outcomes and follow-up information. The registry lists some related secondary outcomes, but the primary endpoint remains the core-lab-judged radiographic composite.

The endpoint is therefore best read as a comparison of the recorded frequency of the defined imaging finding by 1 year. It should not be interpreted as a complete account of every potential benefit or harm of the procedure, nor as evidence of the biological mechanism that might explain the imaging results.

7. Results Posted in the Registry

• 10-caliber Coils: 18.9% (20/106) versus 25.0% (26/104) on control; risk difference -6.1 percentage points (95% CI -17.3 to 5.0), risk ratio 0.75 (0.45–1.26); unadjusted two-proportion z-test p = 0.283.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Packing Density

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • 10-caliber Coils: mean 26.90 versus 37.00 on control; difference -10.10 (95% CI -15.15 to -5.05), standardized effect d = -0.55; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for 10-caliber Coils than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Modified Rankin Score (mRS) Greater Than 2

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • 10-caliber Coils: 6.6% (7/106) versus 2.9% (3/104) on control; risk difference 3.7 percentage points (95% CI -2.0 to 9.4), risk ratio 2.29 (0.61–8.61); unadjusted two-proportion z-test p = 0.206.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between 10-caliber Coils and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover different dimensions of the comparison: packing density is a technical measure, serious adverse events concern safety, and modified Rankin Score above 2 is a functional outcome. The posted results therefore add context to the radiographic primary endpoint but do not measure the same thing. A finding on one secondary outcome cannot be substituted for a finding on the primary outcome.

Across the posted secondary comparisons, the pattern is not uniform. The packing-density estimate points to a difference between groups, whereas the modified Rankin Score comparison is less conclusive because its reported interval includes no difference. Serious adverse event counts are posted, but no comparative analysis is reported for those figures. The secondary results therefore do not form a single consistent statistical signal across technical, functional, and safety outcomes.

The registry lists nine outcome measures, while formal reported analyses are not included. When several outcomes are examined, some may appear noteworthy by chance even if there is no underlying difference. Adjusting for multiplicity or prespecifying a hierarchy can help control how multiple comparisons are interpreted; such procedures are not reported in the registry record. The secondary findings should consequently be treated as descriptive or exploratory unless their role in the original analysis plan is known.

The primary result remains the central comparison for the trial’s stated question about major recurrence or residual aneurysm at 1 year. Secondary outcomes can suggest questions for further evaluation, but their different definitions, timeframes, and statistical uncertainty limit how much they can settle the primary question.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Packing Density
• Procedural Serious Adverse Events (SAEs)
• Modified Rankin Score (mRS) Greater Than 2

9. Statistical Interpretation

10. Statistical Methods Explained

The posted comparisons use measures suited to the type of outcome. The primary outcome and modified Rankin Score outcome are binary counts: each participant either met the stated event definition or did not. Packing density is continuous and is reported as a mean with a standard deviation. The meaning of each estimate depends on that outcome scale.

How should a risk difference be read?

A risk difference subtracts the event proportion in one group from the event proportion in the other. The primary comparison is expressed as 10-caliber versus 15-caliber coils. Its estimate of -0.061 indicates a lower observed event proportion in the 10-caliber group in this unadjusted comparison. A value of zero would represent no difference between the groups on this scale. The reported interval runs from -0.173 to 0.050, so it includes zero and spans values in both directions.

A risk difference is an absolute comparison on the event-proportion scale. It is different from a risk ratio, which compares proportions as a ratio, and an odds ratio, which compares odds. The registry also gives relative measures for the binary outcomes, but the risk difference makes the direction and scale of the primary comparison explicit. None of these measures alone explains the clinical importance of the outcome or the circumstances of the participants who experienced it.

What does the p-value contribute?

The primary unadjusted p-value is 0.283. A p-value describes how compatible the observed data are with a specified null model, under the assumptions of the test; it is not the probability that the null hypothesis is true. It does not measure the size of an effect, and it does not replace the estimate or its interval. The registry does not report the original statistical analysis plan, so the posted p-value should be read as an unadjusted comparison rather than as confirmation of every aspect of the trial’s intended analysis.

The packing-density comparison reports p < 0.001. This is an unadjusted p-value for a continuous outcome, not a test of the primary radiographic endpoint. The p-value provides evidence about compatibility with a no-difference model under the analysis assumptions; interpretation also requires the estimated mean difference and its interval. The registry does not report a multiplicity adjustment for the secondary outcomes.

How is the continuous outcome compared?

Packing density is summarized by a mean and standard deviation in each group. The posted means are 37.0 for 15-caliber coils and 26.9 for 10-caliber coils, with standard deviations of 22.2 and 13.0, respectively. The mean difference for 10-caliber versus 15-caliber coils is -10.1, with an interval from -15.15 to -5.051. This expresses the difference on the packing-density scale. The standard deviation describes variation among observations within a group; it is not the uncertainty of the group mean itself.

The registry also reports a pooled standard deviation and a standardized difference for packing density. Standardization expresses a mean difference relative to variability, which can help compare differences measured on different scales. It does not change the original outcome scale or provide a clinical interpretation by itself.

Why do intervals matter?

An interval gives a range of values compatible with the observed estimate under the calculation’s assumptions. Its width is informative about precision: a narrower interval generally indicates greater precision, while a wider interval leaves more uncertainty about the size and direction of a difference. The confidence level for the reported intervals is not stated in the registry record, so it should not be inferred from the values alone.

For the binary primary outcome, the interval includes zero. For packing density, the reported interval for the mean difference does not include zero. These are different outcomes with different scales, and the results should not be combined into a single conclusion. The modified Rankin Score comparison also reports an interval for a risk difference, but it should be interpreted as a secondary result rather than as a substitute for the primary outcome.

What is recalculated and what remains unknown?

The comparisons are simple unadjusted recalculations from posted group summary statistics. The record does not flag a discrepancy between the recalculated values and sponsor results. No adjusted estimates, covariate model, or formal analysis details are reported in the registry record. The reported comparisons therefore do not establish whether the original investigators used a different model, how missing observations were handled, or which analysis population was intended.

In general, randomization can support a fair comparison by reducing systematic differences between assigned groups, while appropriate analysis is needed to preserve that comparison. The registry record does not give enough detail to assess all analysis choices. The numerical estimates remain useful descriptions of the posted group results, but their interpretation should stay within those limits.

11. Confidence Intervals and Precision

The primary risk-difference estimate for 10-caliber versus 15-caliber coils is -0.061, with a reported interval from -0.173 to 0.050. Because that interval includes zero, the posted results are compatible with no difference as well as with differences in either direction. The interval’s breadth also means the estimate does not pin down a narrow range of plausible effects. The confidence level for the interval is not reported in the registry record.

Precision and statistical significance are related but distinct. An interval describes uncertainty around an estimate, whereas a p-value summarizes compatibility with a specified null model. Neither tells whether a difference is clinically important. The primary result’s p-value is 0.283, and the interval gives useful context for understanding the uncertainty that accompanies the point estimate.

The secondary estimates have their own precision. The packing-density interval for the mean difference runs from -15.15 to -5.051. The modified Rankin Score risk-difference interval runs from -0.02 to 0.094. These intervals apply to different outcomes and scales, so their widths should not be compared as though they measured uncertainty in the same units.

Intervals cannot correct for limitations that are not documented, such as missing outcome data, analysis-population choices, or multiplicity. Those details are not reported in the registry record. The posted intervals are therefore best viewed as precision summaries for the stated unadjusted comparisons, rather than a complete account of all sources of uncertainty.

12. 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 planning figures are illustrative calculations based on the observed effect, not the trial’s original design assumptions. For the primary binary outcome, the figures are participants per arm. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The original sample-size justification and the trial’s own design assumptions are not reported in the registry record.

For planning at 100% of the observed primary effect, the figures are 714 participants per arm for 80% power and 955 participants per arm for 90% power. At 75% of the observed effect, they are 1,302 and 1,742 participants per arm, respectively. At 50% of the observed effect, they are 2,998 and 4,013 participants per arm, respectively.

The 80% power column represents the planning number of participants per arm under the stated assumptions for a design intended to have an 80% chance of detecting the specified effect, if that effect and the assumptions were correct. The 90% column describes the corresponding planning target for 90% power. These are forward-looking planning quantities, not a measure of what the completed trial achieved.

Smaller effects require more participants to detect under the same assumptions, which is why the planning figures increase as the assumed fraction of the observed effect decreases. The figures are not observed power. They should not be treated as a post-trial verdict on whether the study was adequate, since they use the observed effect and do not substitute for the missing original design rationale.

For other outcomes, the posted planning figures are also participants per arm; the registry’s event-total convention applies to time-to-event calculations, and no time-to-event outcome is presented in these comparisons. The original design assumptions remain unreported.

13. 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 = 0.250; treatment proportion p₁ = 0.189; average p̄ = 0.219.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.5852 = 1.1470.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5836 = 0.4912.
4. n = (1.1470 + 0.4912)² / (-0.0613)² = 713.6, rounded up to 714 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 <- 0.25                          # control proportion
p1 <- 0.188679245283019                          # 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(1943591)
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 = 714 (80% power), 955 (90% power)
 75% of observed effect: n per arm = 1,302 (80% power), 1,742 (90% power)
 50% of observed effect: n per arm = 2,998 (80% power), 4,013 (90% power)
power.prop.test: 713.6 
Simulated power at n = 714 per arm: 0.795 (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.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists nine outcome measures, including the primary radiographic endpoint and secondary outcomes. However, it reports no formal analyses in the analysis listings. The posted group counts and unadjusted comparisons do not state whether the original investigators designated a hierarchy of outcomes, adjusted for multiple testing, or treated the secondary outcomes as exploratory. Those details are not reported in the registry record.

Multiplicity matters because interpreting many outcomes or comparisons increases the chance that one result will appear statistically notable by chance. A prespecified primary endpoint helps focus interpretation, but it does not by itself explain how all secondary tests were handled. Without the original analysis plan, the unadjusted secondary p-values should not be read as though they were adjusted for the full set of outcomes.

Missing-data information is also limited. The posted group denominators vary by outcome, but the registry does not explain why observations are unavailable for some outcomes or how missing measurements were handled. It does not report imputation methods, sensitivity analyses, or a detailed account of follow-up completeness. No assumptions about missing outcomes should be made from the counts alone.

The analysis population is not reported in the registry record. In particular, the record does not say whether the analyses followed all randomized participants according to assigned group, used a per-protocol population, or applied another approach. The masking target and the original statistical analysis plan are also not reported. These omissions constrain assessment of potential bias and make it difficult to determine whether the posted calculations fully represent the trial’s prespecified analysis.

15. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: stroke, causing morbidity (5.7%), aneurysm rupture during procedure causing morbidity (3.8%), aneurysm rupture during procedure causing mortality (1.9%), stroke, periprocedure causing mortality (1.9%), event unrelated to aneurysm or its treatment causing mortality (1.9%).

The registry reports serious adverse event counts of 7 among 104 participants at risk in the 15-caliber group and 18 among 106 at risk in the 10-caliber group. It also reports other adverse event counts of 8 among 104 and 20 among 106, respectively, and deaths of 2 and 7. These are descriptive figures; the registry does not provide a comparative statistical analysis for them.

The listed serious event terms include stroke causing morbidity and aneurysm rupture during the procedure causing morbidity, as well as several mortality-related terms. Their listed percentages are registry entries, not a basis for attributing an event to a coil type. The record does not provide enough information to determine overlap among event categories or whether counts represent unique participants across categories.

These figures should be read as safety information recorded for the trial, not as proof that an intervention caused or prevented an event. Interpretation is limited by the absence of a reported comparative analysis, details about event ascertainment, and information on how adverse events were classified. No clinical recommendation follows from these counts alone.

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

The primary results describe a numerical difference in the observed frequency of major recurrence or residual aneurysm between the randomized groups. The point estimate is in the direction of fewer recorded primary events with 10-caliber coils, but its interval includes no difference and extends in both directions. The results therefore do not establish a clear difference between coil strategies for this endpoint.

That conclusion is not the same as demonstrating that the strategies are equivalent. Equivalence requires a defined margin and an analysis designed to assess whether the difference falls within that margin. The registry record does not report an equivalence or noninferiority design, nor does it provide a margin. A nonsignificant result alone cannot establish that outcomes are the same.

The results also do not establish that either coil type works or does not work in a broader clinical sense. The endpoint is a specific radiographic composite at 1 year, not a complete measure of health, symptoms, function, or long-term outcomes. The registry’s secondary findings concern distinct measures and have their own uncertainties. They cannot be collapsed into a general claim about overall treatment effect.

Random allocation makes the group comparison informative, but the registry record does not describe the analysis population, missing-data handling, or full analysis plan. The posted estimates should therefore be interpreted as the unadjusted comparisons they are, without assuming undocumented procedures or a particular explanation for the outcomes.

In practical statistical terms, the primary estimate is compatible with a range of possible group differences, including no difference. Further interpretation would require attention to the endpoint’s clinical relevance, the confidence level and analysis methods, follow-up and missingness, and any prespecified approach to secondary outcomes. Those details are not reported in the registry record.

17. Why This Trial Matters Statistically

The trial addresses a focused methodological question: whether changing coil caliber alters a radiographic outcome after aneurysm coiling. Its rationale links coil volume with packing density and proposes that this might affect residual aneurysm or recurrence. The trial is therefore informative statistically because it places a technical measure and a clinically relevant imaging endpoint in the same randomized comparison.

The outcomes illustrate why different measures should not be treated as interchangeable. Packing density is a continuous technical measure, while the primary endpoint is a binary radiographic finding, and modified Rankin Score is a functional outcome. A difference in one measure does not automatically imply a corresponding difference in another. Each must be interpreted on its own scale and with its own uncertainty.

The primary comparison also demonstrates the importance of considering precision alongside a point estimate. The estimated direction alone does not resolve the question when the interval includes no difference and spans possibilities in both directions. A p-value alone would omit that range of plausible values. Reading the estimate, interval, and outcome definition together gives a more complete statistical interpretation.

Finally, the record highlights the value of transparent analysis reporting. Information about the original design assumptions, multiplicity, missing data, and analysis population would help readers judge how the posted results relate to the trial’s intended methods. The randomized comparison is useful, but the limits of the registry record matter when drawing conclusions from its estimates.

18. 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 registry record does not report the original sample-size justification or the assumptions used to plan the trial. The planning calculations based on observed effects are not a substitute for that rationale. The record also does not identify the confidence level for the reported intervals, so the intervals cannot be assigned a level based on the posted values alone.

The masking entry says single, but the masked party or parties and the practical masking procedures are not described. The registry does not report the analysis population, missing-data handling, or follow-up completeness. These gaps limit assessment of how participants with unavailable outcome data were treated and whether the posted estimates correspond to the intended analysis.

The primary endpoint combines major recurrence and residual aneurysm, and the registry does not give separate counts for those components. It therefore does not show whether the overall count was driven more by one component or the other. The primary outcome population is also not described beyond the group counts.

The record lists nine outcome measures but does not report formal analyses or a multiplicity strategy. That leaves uncertainty about the prespecified role of secondary outcomes and whether any adjustment was intended. The serious adverse event counts are descriptive, without a reported comparative analysis, and the registry does not explain possible overlap across event categories.

These limitations do not erase the posted group results, but they narrow what can be concluded from them. The estimates are best understood as unadjusted comparisons in the registry record, with important details of the original analysis and data handling not reported.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: DELTA Trial: Does Embolization With Larger Coils Lead to Better Treatment of Aneurysms Trial — NCT01943591.
• Registry record last updated 2020-01-22; status last verified 2018-12.
• Results first posted 2020-01-22.
• 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.

22. Record Summary

DELTA (NCT01943591) was a completed randomized, parallel-group trial of endovascular coiling with 15-caliber platinum coils versus standard 10-caliber coils for cerebral aneurysms. The registry lists single masking and enrollment of 210.

The primary outcome was major radiographic recurrence or residual aneurysm as judged by a core lab at 1 year. The posted counts were 26 of 104 in the 15-caliber group and 20 of 106 in the 10-caliber group. The unadjusted risk difference for 10-caliber versus 15-caliber coils was -0.061, with an interval from -0.173 to 0.050 and p = 0.283.

The registry also lists packing density, serious adverse events, and modified Rankin Score above 2 as secondary outcomes. The original statistical plan, missing-data approach, analysis population, and multiplicity strategy are not reported in the registry record.