Medical CostsMethods:

• Dependent variable: all allowed professional, facility, and pharmacy charges for first 12 months for each claim• OLS using robust variance estimates• Standard errors were adjusted to account for correlation of outcomes within a specific provider’s practice• Control variables: injury category, sex, age, month claim was filed (to control for fee schedule inflation & variable time window for claim submission), public employer, retrospective rating group, small employer, unemployment rate, higher volume provider, rural provider location, COHE participation*• Sensitivity analysis: subset of claims with no transfers of attending provider (the initial attending provider may not be responsible for downstream events if there are transfers of care)

Results:

• Attending provider type was not a significant predictor of medical costs• Interactions between provider type and injury category were not significant• Results were similar using log transformed or winsorized (highest 2% truncated) costs• Among back sprains only, results were similar with and without control for baseline radiculopathy

Research Objectives To evaluate the effect of SHB 1691 on costs and disability outcomes for injured workers To evaluate NPs in the role of attending provider for injured workers

State Legislation Expanding the Role of Nurse Practitioners in a Workers’ Compensation System:

Effects on Disability and Costs

Jeanne M. Sears, PhC, MS, RN, Department of Health ServicesThomas M. Wickizer, PhD, MPH, Department of Health ServicesBobbie Berkowitz, PhD, CNAA, FAAN, School of NursingGary M. Franklin, MD, MPH, Department of Environmental & Occupational Health Sciences

Time Loss DurationMethods:• Dependent variable: cumulative compensated days lost from work • Cox proportional hazards regression using robust variance estimates, stratified by injury type• Standard errors were adjusted to account for correlation of outcomes within a provider’s practice• Control variables: sex, age, public employer, retrospective rating group, small employer, unemployment rate, higher volume provider, rural provider location, COHE participation*• Sensitivity analysis: subset of claims with no transfers of attending provider (the initial attending provider may not be responsible for downstream events if there are transfers of care)

Results:

• Attending provider type was not a significant predictor of time loss duration• Interactions between provider type and injury category were not significant• Among back sprains only, results were similar with and without control for baseline radiculopathy

University of Washington School of Public Health

& Community Medicine

Contact: jeannes@u.washington.edu Funding: Occupational Epidemiology and Health Outcomes Program, DEOHS, UW; NIOSH ERC Occupational Health Services Research Training Program (#T42 CCT010418; #1 T42 0H008433)

ContextSubstitute House Bill (SHB) 1691 was implemented 7/1/04 in WA State amid concern about disparities in access to care for injured workers in rural areas

• Some providers are reluctant to treat injured workers • NPs provide about 10% of generalist health care in WA

SHB 1691 authorized NPs to independently perform most functions of an attending physician in the workers’ compensation system

• NPs provide safe & cost-effective care in other settings• Little research specific to NPs that treat injured workers

Conclusions• NPs serve injured workers with similar characteristics to those served by PCPs (but are more likely to be rural)

• Attending provider type is not a significant predictor of disability or medical costs for injured workers in WA

• Given the absence of evidence for negative consequences of SHB 1691, decisions regarding this pilot project may reasonably be based on the potential advantages of including NPs as attending providers (such as improved geographic access, increased provider satisfaction, and increased provider choice for claimants)

Data Source & Study DesignData Source: Washington State Department of Labor & Industries (State Fund)

• Administrative claim, medical billing, and enrolled provider data • Population-based data: single payer for 70% of nonfederal claims (other 30% self-insured)

Design: “After-only” policy evaluation• Primary care physicians (PCPs) as benchmark/comparison group

[MDs & DOs: Family Practice (63%), General Practice (13%), Internal Medicine (24%)]• 12-24 months of follow-up (through 6/30/06; data extracted 10/3/06)• Inclusion criteria:

• Accepted claims with accident report filed 7/1/04 through 6/30/05• First medical visit on or after 7/1/04 (date of SHB 1691 implementation)• NP or PCP as first attending provider of record• Claimant 18-70 years old• Indication of treatment at a primary care facility at the first visit (office, clinic, urgent care)• Injury occurred within WA & first attending provider located within WA

• Exclusion criteria:• Fatal & total permanent disability claims• Indication of inpatient, ambulance, or emergency department services at first visit

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

$4,000

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$5,000

0.00

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0.75

1.00

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porti

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f Cla

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n Ti

me

Loss

0 200 400 600 800Cumulative Time Loss Days

PCPs NPs

Kaplan-Meier Survival Curves

Adjusted for Worker, Employer, & Provider Characteristics (N = 29,949)Time Loss Days by First Attending Provider Type

Strengths• Included control for worker, injury, employer & contextual variables• Stakeholder involvement in design• Population-based data with a large number of claims

Limitations• Observational design with possible selection bias (limited severity data & no data on comorbidities)• Time loss is only a rough measure of return to work• Short time frame:

• Unable to evaluate extended time loss• Short allowance for bill processing time (providers have a year to submit bills so costs are underestimates)• Possible learning curve for providers new to WC system

• Successful outcomes are only partially influenced by injury type and process of health care

OLS Model N claims N providers Coefficient 95% CI

All claims 29,949 2,688 $5 (higher for NPs) - $238, $248No transfers 24,683 2,530 - $75 (lower for NPs) - $223, $74

Cox Model N claims N providers Hazard Ratio 95% CI

All claims 29,949 2,688 1.01 (NPs/PCPs) 0.981, 1.047

No transfers 24,683 2,530 1.02 (NPs/PCPs) 0.996, 1.050

Medical Costs by Cost Category and Attending Provider Type Medical Costs by Injury Category and Attending Provider Type

Sample Characteristics

NP PCP p -value

Provider Characteristics n=251 n=2,437

Median annual claim volume 6.0 15.0 <0.01

Located in distressed county 21.5 15.7 0.02 Rural provider (RUCA-based) 22.3 17.4 0.05 COHE* provider 8.8 6.9 NS

Claimant Characteristics n=2,921 n=27,028

Median monthly pre-injury income** $2,112 $2,409 <0.01 Mean age 37.1 38.1 <0.01

Married** 50.2 49.8 NS 1 or more dependents** 41.8 38.0 NS Male 64.9 67.6 <0.01 Worker injured in rural county 53.8 27.9 <0.01 Injury type: <0.01

UE & LE lacerations/contusions † 23.6 22.9Back sprains 13.0 14.9

UE & LE sprains 18.1 17.3Corneal abrasions/conjunctivitis 5.3 4.0

UE & LE fractures 2.6 2.6UE & LE heat burns 1.3 1.0

Other injury 16.9 18.4Carpal tunnel 1.9 2.3Hearing loss 0.8 0.9Other illness 2.5 2.8

Unspecified/multiple 13.9 12.9 Baseline radiculopathy‡ 2.9 3.3 NS

Employment characteristics n=2,921 n=27,028

Mean county unemployment rate 6.9 5.6 <0.01

Public sector employment 6.9 8.8 <0.01 Retrospective rating group at time of injury 53.9 49.0 <0.01 Small employer (< 25 FTE) 30.7 32.3 NS

Claim characteristics n=2,921 n=27,028

Mean claim duration (in days) 129.6 139.3 <0.01

Time loss claim 20.3 23.5 <0.01 Permanent partial disability payment 3.5 4.1 NS Claim closed within 6 months 80.7 78.5 <0.01 Claim closed within 12 months 90.8 89.2 0.01 Claim closed at end of follow-up period 94.0 93.5 NS Claim reopened 0.5 0.6 NS No change in attending provider 83.6 82.3 NS

NOTES * The COHE project provides incentives for occupational health best practices ** Includes time loss claims only due to accuracy and missing data issues (n=6,931)

‡ Within first week of treatment (back sprains only, n=4,417)

Percent of providers

Percent of claims

† UE/LE: upper extremity & lower extremity

Percent of claims

Percent of claims

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NP

PCP