Abstract: SA-PO497
Composite End Points in ADPKD Studies: A Guide for Best Practices
Session Information
- ADPKD: Clinical Studies
October 27, 2018 | Location: Exhibit Hall, San Diego Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidney
- 1001 Genetic Diseases of the Kidney: Cystic
Authors
- Mustafa, Reem, University of Kansas, Kansas City, Kansas, United States
- Baron, David, PKD Foundation, Kansas City, Missouri, United States
- Czerwiec, Frank S., Otsuka Pharma. Devel. & Comm., Inc., Rockville, Maryland, United States
- Yu, Alan S.L., University of Kansas Medical Center, Kansas City, Kansas, United States
- Perrone, Ronald D., Tufts Medical Center, Boston, Massachusetts, United States
Group or Team Name
- for the Polycystic Kidney Disease Outcome Consortium (PKDOC) composite outcomes subcommittee
Background
There is considerable inconsistency in the outcomes reported in Autosomal Dominate Polycystic Kidney Disease (ADPKD) and how they are measured. In this article, we aim to highlight the appropriateness of different outcomes to be included as a component in composite outcomes
Methods
We developed guidance including a summary table for components of the composite end points in ADPKD. We utilized the results of a systematic review and discussions among the Polycystic Kidney Disease Outcome Consortium (PKDOC) composite endpoint subcommittee. The subcommittee consists of Scientists, clinicians, methodologists, manufacturers, patients, advocacy groups representatives, and critical path institute representatives, all with experience in ADPKD. The investigators assessed the face validity of the suggested guidance and used an iterative approach of feedback, revision, and testing.
Results
Table 1 summarizes outcomes that are reported in ADPKD studies and the different ways they can be measured. It also explores pros and cons for including them as part of a composite outcome for ADPKD studies.
Conclusion
Composite end points will continue to be used in ADPKD studies and may be more utilized in-light of new approved treatments. Understanding the unique considerations about the different components and their use in ADPKD studies is essential in developing high quality evidence that will appropriately assess the short and long term effects of different interventions.
Table 1
| Endpoint | Feasibility of collecting data | Event frequency | Acceptability to regulators | Previous body of evidence in a clinical area | Comments |
| Death | Yes | Rare | Yes | Commonly reported as a component of a composite | - Likely more appropriate to use overall mortality -Disease specific mortality requires clear definitions. - Death rate will depend on baseline risk of mortality in the population of interest, which is low in ADPKD -Should be considered but may not apply in all cases (e.g. children). |
| ESRD including preemptive transplant | Yes | Varies depending on genotype, rate of progression and comorbidities | Yes | Commonly reported as a component of a composite | Enrichment strategies are useful to increase the event rate of the outcome. -Clear definitions of ESRD are necessary. |
| Hospitalization | Yes | Varies; Can be affected by patients’ history | Yes | Reported as an outcome but not often part of a composite | Hospitalization due to disease specific Interventions or complications should be very clearly defined and adjudicated |
| Worsening kidney function | Yes | Varies/Frequent | Yes | Commonly reported as a component of a composite | -Reported using different measures (e.g. doubling of serum Cr, 50% reduction in eGFR, reduction of eGFR beyond a certain threshold) -Important to note that the pattern of treatment effects on GFR must be examined, specifically acute effects on eGFR -Need to be aware of hyperfiltartion as a potential confounder to the results of kidney function |
| Hypertension | Complicated if agent affects BP and by concomitant anti-hypertensive use | Frequent | Accepted surrogate | Reported as an outcome but not often part of a composite | -could be unreliable unless very clearly defined. -Reported using different measures (e.g. SBP, DBP, worsening hypertension as defined by “intensified therapy”) - It is important to include the actual BP value |
| Chronic or acute pain / Medication | ? lack of reliable and responsive tools to assess pain and identify cause | Varies/Frequent | Yes when using validated tools | Reported as an outcome but not part of a composite | -Reported using different measures (e.g. significant kidney pain necessitating medical leave, pharmacologic treatment or invasive intervention) -Challenging to distinguish Kidney pain |
| Total Kidney Volume | Varies/ requires CT or MRI | Varies | Varies with different jurisdictions. Not accepted as a clinical outcome but accepted as “reasonably likely surrogate” and “prognostic enrichment biomarker” in the united states | Reported as an outcome but not part of a composite | -Earlier biomarker than worsening kidney function -usually reported as % change of TKV over different periods |
| Activities of Daily Living/Quality of life | Yes/ requires validated tools | Varies | Yes when using validated tools | Reported as an outcome but not part of a composite | -Many different ADLs could be measured using validated tools. -There are also “accepted” patient reported outcome measures that should be considered |
| Proteinuria | Varies/ Complicated by concomitant medication use and variability in ways to measure it | Varies | No | Inconsistent reporting | -Not a common feature of ADPKD -Reported using different measures (e.g. Urine protein/Creatinine ration, time to the doubling of the baseline urine protein-to-creatinine) |
| Radiological appearance of the kidney | No | Varies | No | Not often reported and is not part of a composite | -Technology not mature and validated. “Textural analysis.” |
| Girth | Yes/ requires validated tools | Varies | Yes, when using validated tool | Not often reported and is not part of a composite | -Could be well measured with a PRO -Multiple factors affect Girth including liver size. -Organ enlargement is only a measure of late disease - May be considered cosmetic |
| Kidney stones and Kidney infections | Yes | Varies but relatively infrequent | Yes (clinically meaningful) | Not often reported and is not part of a composite | -Infrequent and may not be a good component in a composite |
| Cardiovascular outcomes | Yes | Varies depending on comorbidities but relatively infrequent | Yes | Not often reported and is not part of a composite | -Unlikely to occur in early ADPKD disease -May be considered a safety endpoint depending on the agent being investigated |