Office of Compensation Analysis and Support 

Program Evaluation Report

Document Number: 

OCAS-PER-016 

Effective Date: 

9/25/2007 

Revision No. 0

Implementation of IREP procedure for claims near 50% probability of 

causation Page 1 of 3 

Author: __Signature on file __________ Date: __9/25/2007_ Brant Ulsh, Research Health Scientist 

Approval: ___Signature on file____________ Date: __9/25/2007_ J.W. Neton, Associate Director for Science 

Supersedes: None 

ISSUE 

AUTHORIZATION 

DATE 

EFFECTIVE 

DATE 

REV. 

NO. DESCRIPTION 

9/25/2007 9/25/2007 0 

New document to evaluate the effect of 

implementing a new IREP procedure on 

previously completed claims 

1.0 Description

Prior to June 6, 2006, each case with a probability of causation (PC) value of at least 45% but 

less than 50% at the upper 99th percentile credibility limit (C.L.), using the default NIOSH-IREP 

settings (simulation sample size = 2000, random number seed = 99), was processed by increasing 

the simulation sample size to 10,000, choosing a new random number seed, and rerunning each 

cancer associated with the claim in NIOSH-IREP. The resulting upper 99% C.L. of PC 

determined the case outcome, supplanting the initial PC value that had been obtained using a 

sample size of 2000. This procedure was employed in order to provide better statistical precision 

for cases approaching the compensation threshold of 50% (1). 

To achieve even greater statistical precision for cases close to the compensation threshold, a 

revised procedure was adopted on June 6, 2006 (2) and replaced the procedure described above. 

Revised procedure for cases with PC values close to 50% (effective 6/6/06)

For “single cancer” cases in which the initial PC is equal to or greater than 45% but less than 

50% using the default sample size of 2000 and default random number seed of 99: 

Step 1: The simulation sample size is increased to 10,000. 
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Step 2: 30 additional IREP runs are performed, using a new random number seed for each run. 

Step 3: The average value (arithmetic mean) of the upper 99% C.L. of PC of the 30 runs is 

calculated. The average value of the 30 runs determines the outcome of the case. 

For cases with more than one cancer in which the initial “combined” PC calculated from the 

“multiple primary” equation is equal to or greater than 45% but less than 50%, 30 runs are 

performed for each primary cancer per steps 1 and 2 above. The average value (arithmetic mean) 

of the upper 99% C.L. of PC of the 30 runs for each cancer is then entered into the online 

“multiple primary” equation. The newly calculated PC, based upon the average PC value of 

each cancer as entered into the equation, determines the outcome of the case. 

The Department of Labor (DOL) implemented this procedural change on June 6, 2006 (3), and 

NIOSH revised the NIOSH-IREP User's Guide accordingly. The most recent edition of the 

User’s Guide is Version 5.5.2 (4). 

2.0 Evaluation

In accordance with the procedural change described above, claims with a PC ≥45% but <50% 

completed by NIOSH and submitted to DOL prior to 6/6/06 were eligible for review. For quality 

assurance purposes, however, it was decided to extend the eligibility date through 6/30/06 to 

allow for possible processing errors during NIOSH’s transition to the new policy. For claims 

that had been reworked due to DOL returns, only the most recent revision of each such claim 

was considered. A database search identified 109 claims that met the above criteria. 

It should be noted that most of the “45.00-49.99% PC” cases forwarded to DOL from June 2005 

to June 2006 had already been subjected by NIOSH to 30 IREP runs in order to establish an 

average PC value. This is because NIOSH used the “30 run” procedure as an in-house pilot test 

before DOL adopted it as official policy on June 6, 2006. Although NIOSH submitted those 

claims to DOL in “single IREP run” format in accordance with pre-6/6/06 policy, the average PC 

value (based on 30 IREP runs) was below 50% for each such claim involved in the pilot test. 

Thus, for those cases in which earlier “30-run” records were available (59 of the 109 claims 

evaluated), it was possible to rely upon the existing results rather than rerun the claims. 

For claims that had not already been subjected to 30 IREP runs per cancer (50 of the 109 claims 

evaluated) as part of the pre-6/6/06 pilot test described above, 30 new IREP runs were conducted 

for each cancer to establish the average PC value for each claim. Since many of these claims 

were “multiple cancer” cases (i.e., more than 1 cancer was reported per claim), 30 new IREP 

runs were conducted for 91 separate cancers. For these 50 claims that required 30 new IREP 

runs to establish a new PC value, the average difference between the original PC (based on 1 

IREP run per cancer) and the new PC (based on the arithmetic mean of 30 runs for each cancer) 

was 0.04 percentage points. The largest increase in PC (30-run average compared to the original, 
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single run value) was 2.27 percentage points, and the largest decrease was 2.71 percentage 

points. The newly established average PC value based on 30 IREP runs remained below 50% for 

each claim. A breakdown of the 109 evaluated claims is displayed in Table 1. 

Table 1: Claims with a probability of causation ≥45% but <50% completed by NIOSH and 

submitted to the Department of Labor prior to 7/1/06 

Type of Claim Number 

of Claims 

Claims With 30 IREP 

Runs From Pre6/6/06 Pilot Test1

Claims 

Requiring 30 

New IREP 

Runs 

Claims in Which the 

Average PC Value 

(Based on 30 IREP Runs) 

Changed to ≥50% 

Single cancer 54 27 27 0

Multiple cancers 55 32 23 0

Total 109 59 50 0

1

See text 

3.0 Resolution or Corrective Action

A total of 109 previously non-compensable claims with PC values of 45% or greater were 

evaluated. The average PC value remained below the 50% compensation threshold for each of 

the 109 claims. An itemized list of claims was provided to DOL containing the final evaluation 

result for each of the 109 claims. 

4.0 Effect of other PER issues

The IREP runs conducted for this PER utilized the latest version of the dose estimate submitted 

by NIOSH to the Department of Labor. If subsequent technical modifications have been made 

that increase the dose estimate in any of these claims, NIOSH, as part of its ongoing review 

process, will request the return of almost all of these claims. The exception to this would be the 

situation in which it could be readily demonstrated that the change would not increase the 

probability of causation to greater than 45% without performing a new dose estimate. 

5.0 References

1) Senes Oak Ridge Inc., under contract with NIOSH. User’s Guide for the Interactive 

RadioEpidemiological Program (NIOSH-IREP), Version 5.2. January 15, 2003. 
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2) National Institute for Occupational Safety and Health, Office of Compensation Analysis and 

Support. New procedure for resolving cases close to 50% probability of causation 

(http://www.cdc.gov/niosh/ocas/ocasirep.html). June 6, 2006. 

3) U.S. Department of Labor, Employment Standards Administration, Office of Workers’ 

Compensation Programs. EEOICPA Transmittal No. 06-09: Revision to Chapter 2-600 Section 

16, Federal (EEOICPA) Procedure Manual. June 6, 2006. 

4) Senes Oak Ridge Inc., under contract with NIOSH. User’s Guide for the Interactive 

RadioEpidemiological Program (NIOSH-IREP), Version 5.5.2. June 2007.