Safety and Pharmacokinetics of IgPro20 and IgPro10 in Adults With Systemic Sclerosis (SSc): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Pharmacokinetics of IgPro20 and IgPro10 in Adults With Systemic Sclerosis (SSc) (NCT04137224), a randomized phase 2 study. The primary outcome is Number of Participants With at Least One Adverse Event (AE) for IgPro20.

2. Clinical Question

The study was a Phase 2, multicenter, randomized, open-label, crossover trial. Its stated aims included evaluating the safety, tolerability, and pharmacokinetics of IgPro20 in participants with dcSSc, as well as characterizing the pharmacokinetics and safety of IgPro10. Relative bioavailability was among the stated pharmacokinetic aims. Those aims are broader than the primary safety endpoint.

In a crossover design, participants are assigned to sequences that receive treatments in different orders. The sequence labels therefore describe treatment order, not separate populations recruited into unrelated parallel trials. The primary endpoint counts participants with at least one adverse event while receiving IgPro20. That count alone does not establish whether an event was caused by treatment, how severe or prolonged it was, or whether one route of administration is preferable.

3. Trial Design

This was a Phase 2, randomized, open-label, crossover study in adults with diffuse cutaneous systemic sclerosis. The registry lists enrollment of 27 and a completed study. The record gives a start date of 2019-09-19 and a primary completion date of 2022-05-17. The sponsor was CSL Behring. The posted study title identifies IgPro20 as subcutaneous immunoglobulin and IgPro10 as intravenous immunoglobulin.

Randomization assigned participants to one of two sequences. Sequence A began with IgPro20 and then switched to IgPro10; Sequence B began with IgPro10 and then switched to IgPro20. The described IgPro20 regimen was a total dose of 0.5 grams per kilogram over 2 sessions per week as a subcutaneous injection for up to 16 weeks. The described IgPro10 regimen was a total dose of 2 grams per kilogram over 2 to 5 sessions on consecutive days every 4 weeks as an intravenous infusion for up to 16 weeks. The registry record does not report further details of the period transition or other crossover procedures.

Open-label means the study was not masked according to the registry. That matters when interpreting safety reporting: participants and study staff were not described as blinded to treatment assignment. The endpoint is based on recorded adverse events, and the record does not describe procedures intended to reduce the potential influence of treatment awareness on event reporting or assessment.

The registry reports 13 participants in each sequence for the IgPro20 primary outcome. For the IgPro10 secondary safety outcome, the sequence-specific counts are 13 and 14. These endpoint-specific denominators should be read as reported, not assumed to represent an identical analysis set at every outcome. The record describes the primary safety analysis set as participants who received at least one infusion of either study drug, with participants who received IgPro20 analyzed for the IgPro20 outcome.

The study also included pharmacokinetic outcomes, such as relative bioavailability, area under the concentration curve, maximum plasma concentration, and trough concentration. The registry lists 43 outcome measures and 25 posted secondary outcomes, while no reported analyses are listed for the secondary outcomes described in the record. The registry record does not report a sample-size justification, an interim-analysis plan, or enough statistical-plan detail to establish how all outcomes were intended to be analyzed.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: A total of 30 participants were screened, of which 27 participants were enrolled and randomized to Sequence A or Sequence B in this study.

Treatment Period 1 (Week 1 to Week 16)

Reasons for not completing this period:

Treatment Period 2 (Week 17 to Week 32)

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Safety analysis set included all participants who received at least 1 infusion of IgPro20 or IgPro10. Participants who received IgPro20 were analyzed.

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: Safety analysis set included all participants who received at least 1 infusion of IgPro20 or IgPro10.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With at Least One Adverse Event (AE) for IgPro20, measured over From first dose of study drug through last follow-up visit (up to 36 weeks).

The primary endpoint is the number of participants with at least one adverse event for IgPro20. The registry defines an adverse event as an untoward medical occurrence in a participant given a pharmaceutical product; it need not have a causal relationship with treatment. It may include an unfavorable sign, symptom, disease, or clinically significant laboratory finding that occurs in temporal association with use of the product, whether or not considered related.

The endpoint covers the period from the first dose of study drug through the last follow-up visit, up to 36 weeks. It reduces each participant’s event experience to a yes-or-no classification: at least one adverse event or none. This makes the outcome interpretable as a participant count, but it does not distinguish one event from multiple events in the same person, describe event duration, or grade event severity. Nor does the count by itself identify whether an event was judged related to IgPro20.

Such an endpoint is used to summarize how many participants experienced any recorded adverse event during the defined observation period. It is relevant to safety monitoring because it captures a broad range of medical occurrences rather than only events attributed to treatment. The trade-off is that broad counting can combine events with different clinical meanings. The registry separately lists serious adverse-event information, but the primary endpoint is the broader count of participants with at least one adverse event.

The outcome is reported for IgPro20 by randomized sequence, not as a pharmacokinetic measure or a measure of disease response. It therefore addresses the frequency of participants with recorded events during IgPro20 exposure, while leaving questions about causal attribution, event burden, and comparative treatment benefit outside the endpoint’s scope.

7. Results Posted in the Registry

• Sequence B: IgPro20: 69.2% (9/13) versus 69.2% (9/13) on control; risk difference 0.0 percentage points (95% CI -35.5 to 35.5), risk ratio 1.00 (0.60–1.67); unadjusted two-proportion z-test p = 1.000.

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.

Number of Participants With at Least One AE for IgPro10

• 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:
  • Sequence B: IgPro10: 57.1% (8/14) versus 38.5% (5/13) on control; risk difference 18.7 percentage points (95% CI -18.4 to 55.7), risk ratio 1.49 (0.65–3.39); unadjusted two-proportion z-test p = 0.332.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sequence B: IgPro10 and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Participants With at Least One AE for IgPro10

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Sequence B: IgPro10: 57.1% (8/14) versus 38.5% (5/13) on control; risk difference 18.7 percentage points (95% CI -18.4 to 55.7), risk ratio 1.49 (0.65–3.39); unadjusted two-proportion z-test p = 0.332.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sequence B: IgPro10 and the control. The interval gives the range of effects that remain compatible with the data.

Number of Participants With at Least One TEAE for IgPro10

• 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:
  • Sequence B: IgPro10: 57.1% (8/14) versus 38.5% (5/13) on control; risk difference 18.7 percentage points (95% CI -18.4 to 55.7), risk ratio 1.49 (0.65–3.39); unadjusted two-proportion z-test p = 0.332.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Sequence B: IgPro10 and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes span safety and pharmacokinetic questions. The registry lists relative bioavailability, concentration-curve measures, maximum and minimum plasma concentrations, and additional safety outcomes. These outcomes address different aspects of exposure and tolerability, so they should not be treated as interchangeable confirmations of the primary adverse-event count. The registry record lists 25 posted secondary outcomes, but no reported analyses are listed for the secondary outcomes described in the record.

The available IgPro10 participant-count outcome is directionally different from the primary IgPro20 count in its observed sequence pattern, but its interval is broad and includes no difference. This does not overturn or validate the primary result. The two outcomes concern different study drugs, and both are reported by treatment sequence in a crossover design. They are not independent replications of a single primary comparison, nor do they by themselves isolate a treatment effect adjusted for order or period.

Unadjusted secondary results generally carry less inferential weight when many outcomes are assessed. General statistical context: testing multiple outcomes increases the opportunity for chance findings, particularly if each result is interpreted without accounting for the full set of tests. The registry record does not report a multiplicity adjustment or a prespecified hierarchy that would identify which secondary results should receive confirmatory interpretation. Consequently, secondary numerical patterns are best considered descriptive unless a reported analysis plan supports stronger claims.

Pharmacokinetic outcomes can inform how drug concentrations vary over time, but their interpretation requires the relevant estimates, uncertainty, and analysis details. The listed outcome names alone do not establish whether one regimen achieved a particular exposure or how precisely any pharmacokinetic contrast was estimated. Overall, the secondary outcomes add breadth to the study’s aims, while the available record does not provide a basis for drawing a unified confirmatory conclusion across them.

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

• Relative Bioavailability (%F) of IgPro20
• Area Under the Concentration Curve to the End of the Dosing Period (AUC0-tau) for IgPro20
• Area Under the Concentration Curve up to the Last Measurable Concentration (AUC0-last) for IgPro20
• Maximum Plasma Drug Concentration (Cmax) for IgPro20
• Minimum Plasma Drug Concentration (Ctrough) for IgPro20 in Sequence A
• Minimum Plasma Drug Concentration (Ctrough) for IgPro20 in Sequence B
• Area Under the Concentration Curve to the End of the Dosing Period (AUC0-tau) for IgPro10
• Area Under the Concentration Curve up to the Last Measurable Concentration (AUC0-last) for IgPro10

9. Statistical Interpretation

10. Statistical Methods Explained

General statistical context: a participant-level binary endpoint records whether each participant did or did not experience the defined event. The count and denominator describe how many participants had at least one event among those analyzed. This differs from an event-rate analysis, which would account for the number of events or the amount of time participants were observed. The primary endpoint counts participants, not events.

What does the risk difference describe?

General statistical context: a risk difference is the event proportion in one group minus the event proportion in the other group, expressed on the probability scale. A value of 0 corresponds to equal observed proportions. Positive and negative values indicate opposite directions of the comparison, depending on which group is subtracted from which. The registry comparison is labeled Sequence B relative to Sequence A. Its primary estimate is 0.0, reflecting the identical reported counts and denominators. The IgPro10 secondary estimate is 0.187. These estimates describe the particular sequence comparisons reported; they should not be mistaken for direct estimates of an isolated drug effect in a crossover model.

What does the confidence interval add?

General statistical context: a confidence interval gives a range of values compatible with the observed data under the calculation’s assumptions. It conveys precision as well as direction. A wide interval means the data are consistent with a broad range of possible underlying differences. For the primary outcome, the 95% confidence interval runs from -0.355 to 0.355. For the IgPro10 secondary outcome, it runs from -0.183 to 0.557. Both ranges include 0, so neither interval rules out no risk difference. Their breadth also means that the estimates do not tightly pin down the possible difference.

How should the p-values be read?

General statistical context: a p-value measures how unusual the observed data, or more extreme data, would be under a specified null model. It is not the probability that the null hypothesis is true, and it does not measure the size or importance of a difference. The primary unadjusted p-value is 1.0; the IgPro10 secondary unadjusted p-value is 0.332. The registry record does not report the full testing procedure or model details behind these comparisons. These p-values therefore should be read alongside the counts and confidence intervals, not as standalone conclusions.

What does the crossover structure imply?

General statistical context: crossover trials assign participants to treatment sequences, and each participant may receive more than one treatment over time. This structure can allow within-participant comparisons, but valid analysis can depend on period, sequence, and carryover considerations. The posted safety comparison is by sequence for the relevant drug, and the registry record does not report an analysis that describes how within-participant dependence or period effects were handled. The sequence comparison should not be represented as a treatment comparison that accounts for those factors unless such an analysis is reported.

What are the planning illustrations?

The posted planning illustrations use the observed IgPro10 effect as a starting point and show participants per arm for 80% power and participants per arm for 90% power under stated assumptions: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They show planning for 100%, 75%, and 50% of the observed effect. The registry record does not report these illustrations as the trial’s original design justification. They are not observed power, do not show the probability that the study detected an effect after completion, and are not evidence that the trial was designed around those values.

The planning numbers are sensitive to the assumed effect. Smaller assumed effects require larger planned groups under the stated calculation. Such illustrations can help readers understand how uncertain estimates relate to future design choices, but they cannot resolve the uncertainty in this study or substitute for a prespecified design rationale. The sample-size assumptions describe equal allocation and a two-arm calculation; the study itself is a randomized crossover trial, so the illustration should not be taken as a complete design calculation for this particular study.

What is not established by the posted analysis?

The registry lists 43 outcome measures and reports no analyses for the secondary outcomes included in the record. The absence of reported analyses means readers cannot assess an adjusted model, a crossover-specific treatment estimate, or the analysis strategy for pharmacokinetic endpoints from those entries. The record also does not report a multiplicity procedure, an interim-analysis plan, or a sample-size justification. Those omissions limit what can be inferred about the planned statistical hierarchy and the intended precision. They do not establish that no such procedures existed outside the registry record.

11. Confidence Intervals and Precision

The primary estimate is a risk difference of 0.0 for Sequence B compared with Sequence A. Its 95% confidence interval is -0.355 to 0.355. The interval includes 0, the value corresponding to no difference, and extends to differences in both directions. The identical observed counts do not remove uncertainty: with 13 participants in each sequence, the data remain compatible with a range of underlying event-frequency differences.

The IgPro10 secondary risk difference is 0.187, with a 95% confidence interval from -0.183 to 0.557. This range also includes 0 and permits effects in either direction. Its width indicates limited precision for the sequence comparison. A point estimate is a single summary of the observed data, whereas the interval makes visible how much uncertainty remains around that summary.

General statistical context: confidence intervals are not a guarantee that the true value lies within the reported range, nor do they state the probability that a particular effect is true. They are interpreted under the assumptions of the method used to calculate them. The registry record does not report enough detail to evaluate all modeling assumptions for the comparisons, especially any treatment of crossover structure. The posted intervals should therefore be read as the uncertainty attached to the reported comparisons, not as confirmation that every design feature was incorporated.

The small endpoint-specific groups and broad intervals make it difficult to distinguish among plausible values of the underlying risk difference. A nonsignificant p-value does not demonstrate equivalence or show that clinically relevant differences have been excluded. No equivalence margin is reported in the registry record. The results are most informative as descriptions of the observed counts together with the wide uncertainty around sequence-level differences.

12. Multiplicity, Missing Data and Analysis Populations

The registry lists 43 outcome measures and 25 posted secondary outcomes. When a study examines many outcomes, the chance of observing an apparently notable result by chance can rise if each is assessed separately. General statistical context: multiplicity procedures or a prespecified outcome hierarchy can help control how a family of tests is interpreted. The registry record does not report a multiplicity adjustment, a hierarchy for confirmatory testing, or a complete statistical analysis plan. The unadjusted secondary p-values should therefore be treated cautiously and should not be read as confirmatory evidence on their own.

The record reports no analyses for the secondary outcomes described in the available entries. That limits assessment of how the broader outcome set was handled and whether reported secondary values came from prespecified analyses. It does not prove that analyses were not conducted elsewhere; it means that the relevant details are not reported in the registry record.

The primary safety analysis set is described as all participants who received at least one infusion of IgPro20 or IgPro10, with participants who received IgPro20 analyzed for the IgPro20 outcome. The record does not report a separate detailed accounting of exclusions, missing endpoint values, or methods used to handle missing data. It is therefore not possible to determine from the registry record whether missingness affected the posted estimates or whether any sensitivity analyses were used. The different denominators reported across the drug-specific outcomes should be retained as stated rather than reconciled by assumption.

The registry record also does not report an interim-analysis plan, a detailed sample-size justification, or a complete account of the planned statistical methods. These omissions limit evaluation of the intended type I error control, analysis population definitions across all outcomes, and the relationship between the completed enrollment and the precision sought by the investigators. They should be described as reporting limitations, not as evidence that no such plans or procedures existed outside the registry record.

13. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: upper gastrointestinal haemorrhage (7.7%), chest pain (7.7%), chronic gastritis (7.7%), vomiting (7.7%), dehydration (7.7%).

The registry lists serious adverse events by treatment and sequence, including the number at risk and the number affected. For IgPro20, serious adverse events affected 2 of 13 participants in Sequence A and 3 of 13 in Sequence B. For IgPro10, they affected 1 of 13 in Sequence A and 1 of 14 in Sequence B. The record lists zero deaths in each of the four treatment-sequence groups.

The serious-event terms listed among the top terms are Upper gastrointestinal haemorrhage, Chest pain, Chronic gastritis, Vomiting, Dehydration, and Myocardial infarction, each reported as 7.7%. These listings do not establish that the events were caused by either study drug. An adverse event is defined in the registry as a medical occurrence that need not be causally related to treatment, and the listed terms are not a substitute for case-level descriptions or attribution information.

These counts are descriptive and based on small groups. They do not provide a precise estimate of the frequency of rare serious events, and comparisons across sequence groups should not be treated as definitive treatment effects. The registry record does not report enough detail to assess event timing, recurrence, relatedness, or the full clinical context for each serious event. Zero deaths in the listed groups is a reported count, not evidence that mortality risk is absent.

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

The primary result means that the posted counts of participants with at least one adverse event during IgPro20 exposure were the same in the two randomized sequences: 9 of 13 in each. The estimated risk difference is 0.0, but the 95% confidence interval from -0.355 to 0.355 shows substantial uncertainty around the sequence comparison. The observed equality is a statement about this sample, not proof that the underlying event frequencies are identical.

The result does not establish that IgPro20 has no adverse effects. The endpoint includes any qualifying medical occurrence whether or not considered related to treatment. It also does not determine whether any event was caused by IgPro20, describe event severity or recurrence, or compare clinical benefit. The posted safety count cannot answer pharmacokinetic questions, despite pharmacokinetics being among the study’s stated aims.

The comparison is between randomized sequences in a crossover study, not a straightforward comparison of participants assigned permanently to IgPro20 versus participants assigned permanently to IgPro10. Each sequence received both drugs in different orders. The registry record does not report a crossover-specific model that would allow readers to assess period, sequence, or carryover considerations. The comparison should therefore be kept within the bounds of the analysis as posted.

The secondary IgPro10 result is also uncertain, with a risk difference of 0.187 and a 95% confidence interval from -0.183 to 0.557. It is not a basis for a stronger conclusion when viewed alongside the primary outcome, especially because it is secondary and no reported analysis is listed for it in the registry record. Neither the primary nor secondary count establishes safety in populations beyond the participants studied.

Overall, the registry results describe event counts in a completed Phase 2 study of adults with dcSSc. They do not settle whether sequence-level differences exist, whether events were treatment-related, or how the study’s pharmacokinetic aims were met. The record’s missing statistical and missing-data details further limit interpretation. These findings are not medical advice and do not determine an individual treatment decision.

15. Why This Trial Matters Statistically

This trial illustrates why a matching observed count is not the same as a precise estimate. The primary IgPro20 outcome has 9 participants with at least one adverse event in each sequence, yet the confidence interval still spans differences in either direction. Reporting both the counts and interval keeps the interpretation anchored to the observed data while making uncertainty visible.

The crossover design also highlights the importance of matching the statistical interpretation to the assignment structure. Participants were randomized to treatment order, and each sequence received both study drugs. A sequence-level risk difference is not automatically equivalent to a treatment effect that accounts for within-participant comparisons, periods, or possible carryover. The registry record does not report the details needed to establish whether those features were addressed in a model.

The study’s stated aims combine safety, tolerability, and pharmacokinetics. Those objectives produce outcomes with different meanings and analytical requirements. A broad adverse-event count cannot answer a concentration-curve question, while a pharmacokinetic measure cannot by itself summarize the number of participants experiencing adverse events. Keeping endpoint interpretation specific prevents a result in one domain from being used as evidence in another.

Finally, the record shows why secondary outcomes and planning calculations require context. Many outcomes are listed, but no secondary analyses are reported in the available entries and no multiplicity strategy is reported. The planning illustrations are explicitly based on observed effects and stated assumptions, not on the trial’s own design rationale or observed power. Together, these features make transparent reporting of analysis plans, denominators, uncertainty, and outcome hierarchy essential to sound statistical reading.

16. 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.

Several limitations are specific to interpreting this study from the registry record. The endpoint-specific IgPro20 groups contain 13 participants each, and the IgPro10 groups contain 13 and 14 participants. The confidence intervals are broad, so the comparisons do not tightly estimate possible sequence differences. Small groups also limit the ability of descriptive counts to characterize less common events.

The trial is a crossover study, but the posted comparisons are presented by randomized sequence. The registry record does not report whether the analysis accounted for within-participant dependence, period effects, or carryover. Without those details, the reported sequence estimates should not be promoted to fully adjusted treatment effects. The open-label design is another interpretive consideration for adverse-event reporting, although the record does not establish whether or how awareness influenced reporting or assessment.

The primary endpoint counts participants with at least one adverse event, rather than event frequency, severity, duration, relatedness, or recurrence. Serious adverse-event listings provide additional descriptive information, but the record does not report enough case-level detail to assess causality or clinical context. The listed serious-event terms and zero deaths do not settle the overall safety profile.

The record lists many outcome measures but does not report analyses for the secondary outcomes described in its entries. It does not report a multiplicity procedure, detailed missing-data methods, an interim-analysis plan, or a sample-size justification. It is therefore not possible to evaluate those aspects of the statistical plan from the registry record. These are limitations of the available reporting and do not prove that procedures were absent outside the record.

Lastly, the participants were adults with dcSSc in a Phase 2 study. The registry results alone do not establish how well the findings apply to other populations, treatment settings, or longer periods of observation. The follow-up window for the primary endpoint is stated as up to 36 weeks, which defines the observation horizon for that outcome.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Safety and Pharmacokinetics of IgPro20 and IgPro10 in Adults With Systemic Sclerosis (SSc) — NCT04137224.
• Registry record last updated 2024-02-05; status last verified 2023-05.
• Results first posted 2024-02-05.
• 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.

20. Record Summary

The registry describes a completed, Phase 2, multicenter, randomized, open-label, crossover study of IgPro20 and IgPro10 in adults with diffuse cutaneous systemic sclerosis. Enrollment was 27. Participants received one of two treatment sequences, beginning with IgPro20 or IgPro10 and then crossing over to the other treatment.

The primary endpoint was the number of participants with at least one adverse event for IgPro20 from first dose through last follow-up, up to 36 weeks. The posted count was 9 of 13 in each sequence, with a risk difference of 0.0 and a 95% confidence interval from -0.355 to 0.355. The record also lists serious adverse-event counts and pharmacokinetic and other safety outcomes.

The reported comparison is imprecise and is a sequence-level summary. The registry record does not report a complete statistical plan, multiplicity approach, detailed missing-data methods, or sample-size justification. Secondary outcomes are listed, but no reported analyses are included for the secondary outcomes described in the record. The findings should be read as descriptive registry results rather than as a definitive comparison of treatment effects.