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Table 3 Study design for cost comparisons in worker’s compensation plans

From: A systematic review comparing the costs of chiropractic care to other interventions for spine pain in the United States

First author

Year

Location/Payer type

Data type/Source

Data start -Data end

Indication/Duration

Inclusion

Exclusion

# Insured/# Eligible/# Included

Butler[39]

2010

National/Self-insured employers

1. Claims, 2. Billing, 3. Patients/ASU Healthy Back Study

1/1/1999 - 6/30/2002

Occupational back pain/Any

Incident back injuries

NR

NR/1,831/984a

Cifuentes[37]

2011

National/Private insurer

Claims/Liberty Mutual

1/1/2006 – 12/31/2006

Lower back, sacrum, coccyx, multiple trunk Any

1. Nonspecific low back pain cases, and 2. Sprain or strain injury

1. Medical only claims; 2. Previous WC claims; 3. Temporary disability < seven days; 4. <four visits to PT/DC; 5. First visit >14 days after injury; 6. Health maintenance period < seven days

NR/11,420/894

Gilkey [35]

2008

Colorado/Quasi state agency

Claims/Pinnacol Assurance

1/1/2000 - 12/31/2002

Nonspecific low back injury/Any

Closed claims for nonspecific low back injuries

1. Multiple providers; 2. Hospitalization; 3. Surgery

NR/10,262/2,456

Jarvis [38]

1997

Utah/Nonprofit insurer

Claims/Worker Compensation Fund of Utah

1/1/1986 - 12/31/1989

Spine injuries/Any

2.5 % sample of NCCI codes for spine injuries in 1986 or 1989

1. Surgical cases; 2. Cases that crossed over from one provider group to another

NR/80,615/1,568

Johnson [34]

1999

California/Private insurer

Claims/Zenith National Insurance Corp.

10/1/1991 - 8/1/1993

Occupational back pain/Any

Closed back claims

1. Surgical cases; 2. Missing data; 3. Did not receive care from PT or DC; 4. Received care from PT and DC; 5. Permanent total disability cases

NR/844/844

Phelan [36]

2004

North Carolina /Various payers

Claims/North Carolina Industrial Commission

1/1/1975 - 12/31/1994

Lumbar or lumbosacral strain/Any

1. Closed injury claims, and 2. Complete data available

NR

96,627/43,650/43,650

  1. adata reported in a secondary study report [47]
  2. ASU Arizona State University, DC doctor of chiropractic, NCCI National Council on Compensation Insurance, NR not reported, PT physical therapist, WC workers’ compensation