# Presentation: 181572

## FDAH Adverse Event Report Re-analysis

**David R. Hustead, D.V.M.**
**Sr. Director, International Technical and Biological Regulatory Affairs **
**Fort Dodge Animal Health**

**January 31, 2005**

## FDAH Adverse Event Collection 

- Professional Services Department
- Technical Support
- Adverse Event Investigations
- Regulatory Compliance
- Customer Support
- 28 DVMs with extensive clinical practice prior to joining industry
- 3 PhDs, 7 Vet Techs, 9 Support Staff

## All reports of suspected adverse events are investigated
To improve the quality of data collected, FDAH routinely pays for diagnostic services including specialist referrals
All reports received, regardless of causality, are recorded and submitted to CVM

- To improve the quality of data collected, FDAH routinely pays for diagnostic services including specialist referrals
- All reports received, regardless of causality, are recorded and submitted to CVM

**FDAH Adverse Event Collection**** **

## Report Categories 
Injection Site Report
Allergy Report
Signs 48 hours & consistent with allergy for species
Non-Allergy Report
Lack of Efficacy Report

- Injection Site Report
- Allergy Report
- Signs ****48 hours & consistent with allergy for species
- Non-Allergy Report
- Lack of Efficacy Report

**FDAH Adverse Event Collection**** **

## Medical Association Assessment

- Based on VICH approved draft guidelines
- Each animal event assessed as a whole
- Three categories
- Medical Association Possible
- Product is at least one of equally plausible explanations for the event
- All events are initially assigned to possible category

## Medical Association Assessment

- Medical Association Unlikely
- Sufficient information exists to establish event is not likely to have been associated with product, or there are other more plausible explanations
- Medical Association Probable
- All the following must be met,
- Reasonable association in time
- Adverse event is reasonable given the known pharmacology and toxicology of the drug
- No other equally plausible explanation

## Comparison to Other Products Is  Difficult

- Monthly oral products
- Administered at home by owner as “treats”
- Rates of use are dissimilar and difficult to know
- Different companies have a variety of systems to collect, investigate, quantify, and submit adverse observations as adverse event reports

## For ProHeart 6, biases that may have stimulated reports of adverse observations are:
ProHeart 6 is an innovative sustained-release product
ProHeart 6 is administered parenterally by veterinarians
Two “Dear Doctor” letters discussing ProHeart 6 safety issues
Widely-disseminated news reports and website postings critical of ProHeart 6

- ProHeart 6 is an innovative sustained-release product
- ProHeart 6 is administered parenterally by veterinarians
- Two “Dear Doctor” letters discussing ProHeart 6 safety issues
- Widely-disseminated news reports and website postings critical of ProHeart 6

- Over-Reporting Bias

## Over-Reporting Bias

- Practitioner presented with diagnostic dilemma
- Oral Preventive
- History rarely includes heartworm preventive administration regardless of diagnostic outcome
- Veterinarian does not make connection that preventive was given within last month
- ProHeart 6
- Veterinarian knows when ProHeart 6 was given
- Likely to make temporal link to ProHeart 6
- Leads to company contact for assistance
- Report submitted to CVM

## Total AERs By Year

- 							         **2003**
**	****       **_**Active**_**	****	**** **_**2001**_**	**_**2002**_**	**_**2003**_**	**_**Market Share**_**     **
**	****	**
- 	Ivermectin + pyrantel	  73	  339	**2331**	         37%
- 	ProHeart 6		677    	2090          **1604**	         24%
- 	Milbemycin	    	113  	  102          **1470**	         21%
- 	CVM Annual AER Summary
- Number of reports for monthly preventives is lower in 2001 and 2002
- In 2003, reporting of AERs for ProHeart 6 is comparable to that of the leading heartworm preventives

## AERs by Year Excluding Inefficacy

- 							         **2003**
**	****      **_**Active**_**	****	**** **_**2001**_**	**_**2002**_**	**_**2003**_**	**_**Market Share**_**      **
**	****	**
- 	Ivermectin + pyrantel	  52	  144	**2194**	         37%
- 	ProHeart 6		677    	2020	**1408**	         24%
- 	Milbemycin	    	113  	  102    	  **722**	         21%
- 	CVM Annual AER Summary
- When inefficacy reports are excluded, the reporting rate for ProHeart 6
- 	remains comparable to that of leading heartworm preventives

## Number of AERs by Quarter

- AVG/QTR thru Q2-04 = 421

## Reporting Rate

- Total numbers of AERs, while valuable, fail to estimate incidence of the event and fail to account for change in use of product
- Reporting rates are calculated by dividing the number of  AERs by the number of doses sold in the same period
- Reporting rate provides a better estimate of incidence

## Reporting Rate By Quarter

- June 01 – May 02  2.45 per 10,000
- June 02 – May 03	  4.35 per 10,000
- June 03 – May 04	  2.13 per 10,000

## Reports Involving Death

- FDA previously presented that there are 485 deaths that are at least possibly related to ProHeart 6
- FDAH was able to review the FDA’s causality assessments in 353 of these reports

## CVM Causality Assessment Scores for Deaths

**Period covered:  June 2001 through May 2004**

**Remotely 18%**

**Possible 77%**

**Probable 5%**

## Reports Involving Death

- FDA assesses 5% as “probably related” to ProHeart 6 (FDA score 3-4)
- FDA assesses 77% as “possibly related” to ProHeart 6
- 	(FDA score 0-2)
- Should “possibly related” assessments support market recall?

## Reports Involving Death

- Scientifically implausible events should be disregarded in conducting a meaningful review
- Remove events with concurrent vaccination
- Remove events with tumors (< 6 weeks)
- Remove events with FDA causality of zero
- 38% of events
- Remove events with incorrect causality assessment

## FDA Causality Assessments

- FDAH carefully reviewed a subset of the available FDA assessment reports
- In 1/3 of these reports,  the FDA assessed events as “possibly related” while FDAH assessed these events as “remotely related”
- 2 examples
- Dog with hemorrhagic episode; found to have significant levels of rodenticide in liver; FDA assessed as “possibly related”
- Dog presented with pain in abdomen 4 months post-ProHeart 6; dog was euthanized and necropsied – hemangiosarcoma of liver diagnosed; FDA assessed as “probably related”

## ProHeart 6 Death Reports in Context

- ProHeart 6 mortality rate
- 500 per 12 million dogs per 2.5 years
- 20 per 1 million dogs per year
- General canine population mortality rate
- 5% per year
- 50,000 per 1 million dogs per year
- Given limitations of passive AE reporting systems, the level of death reported with ProHeart 6 is less than the expected mortality rate in dogs

## FDAH AER Categories

- Allergy Reports (n = 2652)
- Signs include anaphylaxis, urticaria, itching
- Most occur within 48 hours of administration
- Systemic (non-allergy) Reports (n = 2510)
- Could involve any body system
- Signs not typical of “allergy”
- Time period not designated
- AERs in this category may have allergic etiology

## Allergy AERs

- Reporting rate is low
- 1.26 per 10,000 doses sold
- > 80% allergic events are self-limiting and dog returns to normal
- Relative frequency decreases over time
- No breed predilection observed
- Reporting rate similar to FDAH vaccines and other common veterinary products

## FDA has raised concerns about multiple body systems
Anaphylaxis
Convulsions
Liver SGPT/ALT
Liver lesions
Low Platelets
IMHA
It is widely recognized that 
When products cause toxicity it is expected that a single/small number of target organs is affected
In contrast, the wide variety of suspected adverse syndromes assigned to ProHeart 6 is inconsistent with established toxicological principles.

- Anaphylaxis
- Convulsions
- Liver SGPT/ALT
- Liver lesions
- Low Platelets
- IMHA
- It is widely recognized that
- When products cause toxicity it is expected that a single/small number of target organs is affected
- In contrast, the wide variety of suspected adverse syndromes assigned to ProHeart 6 is inconsistent with established toxicological principles.

- Systemic AER

## Non-Allergy AERs

- Expert review by body system
- Neurologic:  Alexander deLahunta, DVM, PhD, DACVIM, Neurology
- Hematologic:  Alan Rebar, DVM, PhD, DACVP, Clinical Pathology
- Hepatic:  Alan Rebar, DVM, PhD, DACVP, Clinical Pathology
- Neoplasia:  Philip Bergman, DVM, PhD, DACVIM, Oncology

## 
Independent experts and FDAH conclude majority of AERs are:

Not causally related to ProHeart 6 and reflect the normal range of diseases occurring in the dog population

- Independent experts and FDAH conclude majority of AERs are:
- Not causally related to ProHeart 6 and reflect the normal range of diseases occurring in the dog population

- Conclusions AER Analysis

## Summary and Conclusions

- Moxidectin based products for use in veterinary medicine are registered in over 70 countries.
- Extensive toxicology studies were conducted in mice, rats, and dogs to support the approval of moxidectin for use in food- producing animals
- In a 1-year dog toxicology study, the daily dosage of moxidectin resulting in a monthly moxidectin exposure that is 454-fold greater than dogs administered the recommended dose of ProHeart 6 resulted in no toxicologically significant findings

## Summary and Conclusions

- The rate of submission of initial ADE reports to CVM decreased in 2003 and 2004, compared with 2002
- ProHeart 6 is subject to substantial over-reporting bias
- Even with over-reporting bias and when corrected for market share the number of AERs associated with ProHeart 6 is similar to major competitors
- ProHeart SR 12 comparison to ProHeart 6 demonstrates similar reporting rates of AERs with an apparently lower reported rate of death

## Summary and Conclusions

- While CVM identified 485 reports of death associated with ProHeart 6, FDAH estimates that only 5% of these reports were scored by CVM as “probably related” to ProHeart 6
- The vast majority of allergic events are self-limiting, and the rate of allergic reports is low and decreasing
- The vast majority of the non-allergic events are not causally related to ProHeart 6, and likely reflect the normal range of disease occurring in canine population

## Summary and Conclusions

- Dr. Glickman and colleagues recently conducted a unique study that evaluated over 7 million dog encounters at veterinary hospitals from 42 states. This landmark study in veterinary epidemiology demonstrated that:
- Concurrent use of vaccines demonstrates significant impact on AE rates
- the safety profile of ProHeart 6 is similar to 2 monthly heartworm preventives

## Summary and Conclusions

- FDAH concludes that ProHeart 6 is a safe and effective product for prevention of heartworm disease