This study quantifies direct medical care costs for individual patients with Parkinson's disease (PD) and projects total national costs of PD. Anonymous, patient-level data on health care utilization and cost were obtained from Medstat's MarketScan Research Databases. Patients were selected for study if they had either two instances of a diagnosis of PD or one diagnosis and two or more prescriptions for PD-related medication. A control group of persons without PD was selected for comparison. Total annual health care utilization and costs were calculated for both PD patients and controls. A total of 20,016 patients with PD were identified and followed up for an average of 853 days. The mean age of the patients was 73.6 years, and 51.2% were women. Total annual direct costs were 23,101 US Dollars (SD 27,529) per patient with PD versus 11,247 US Dollars (SD 16,486) for controls. The regression-adjusted incremental direct cost of PD versus control was 10,349 US Dollars (95% confidence interval, 9,053, 11,645). Adding 25,326 US Dollars in indirect costs, and multiplying by 645,000 cases of PD in the United States, the total cost to the nation is projected to be 23 billion US Dollars annually. This estimate is higher than most previous studies, with important implications for health care delivery systems worldwide.

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This study was sponsored and funded by Gilead Sciences. Ozbay is an employee of Gilead Sciences. At the time that this project and manuscript were developed, Lazarus was an employee of Gilead Sciences and may own stock/stock options. Riehle, Montejano, and Lenhart are employees of Truven Health Analytics, an IBM company, which received funding from Gilead Sciences to conduct this study. Burger and White do research with, and are paid consultants for, Gilead Sciences; they do not own equity and received no personal compensation for the work here. Burger also reports consultancy and advisory board work for Actelion Pharmaceuticals and grants from Gilead Sciences, Actelion Pharmaceuticals, Bayer, and United Therapeutics.

The medical RU and cost data were obtained from the MarketScan Research Database for the years 1998-2003. This database contains inpatient, outpatient and prescription drug data for approximately 14 million individuals of all ages, covered under a variety of fee-for-service and capitated provider reimbursement arrangements, including those with Medicare and private insurance. The work loss estimates were based on the MarketScan Health and Productivity Management Database. Claims for services incurred between 1 January 1998 and 31 December 2003 were screened to identify a cohort of HZ patients based on the presence of at least one International Classification of Diseases, 9th Revision (ICD-9) diagnosis code 053.xx. Each patient was assigned an index date based on the earliest observed occurrence of an HZ diagnosis. A cohort of PHN patients was identified as a subset of the HZ cohort with ICD-9 codes 053.12, 053.13, 053.19 or 729.2x in the period of 90 days to 12 months after the index date. Multivariable regression was used to compare HZ cases with matched controls after adjusting for demographic characteristics, insurance status, co-morbidities and medical expenditure in the 6 months prior to diagnosis for each of the endpoints. Separate regression models were developed, in which age and immune status were stratified. All costs were adjusted to March 2008 values using the medical care component of the Consumer Price Index. The average per patient cost of all HZ cases was $US605 in the first 90 days after diagnosis and $US1052 at 1 year. For the subset with PHN, the average per patient cost of HZ at 1 year was $US3815. For the subset with an immunocompromising condition, the average HZ cost at 1 year was $US1745. The majority of the costs were the result of outpatient visits and prescription drugs. The subset of HZ cases that had both absence hour and short-term disability (STD) records available had 26.5 absence hours and 2.9 STD days. Healthcare utilization, medical care costs and work loss all increased with age for all HZ cases. Based on the results from the present study, the direct medical cost burden of HZ in the US is high, exceeding $US1000 per HZ patient. This direct medical cost may be nearly twice as high in immunocompromised patients and four times as high in the subset of HZ cases with PHN. The direct medical cost burden of HZ may exceed $US1 billion annually in the US. The majority of medical RU and cost burden is incurred by the elderly. Although many people with HZ may no longer be in the workforce, HZ does contribute to lost work time.

BackgroundHerpes zoster (HZ), also known as shingles, is a painful and commonly occurring condition in the United States. In spite of a universally recommended vaccine for use in immunocompetent adults aged 60 years and older, HZ continues to impact the American public, and a better understanding of its current incidence is needed. The objective of the current study is to estimate the overall and age- and gender-specific incidence rates (IRs) of HZ among an immunocompetent US population in 2011 following availability of a vaccine.MethodsClaims data from the Truven Health MarketScan® Research databases between 01/01/2011 and 12/31/2011 were extracted. Immunocompetent adult patients, enrolled as of January 1, 2011 were analyzed. The denominator was defined as eligible subjects who were immunocompetent, had no evidence of zoster vaccination, and no diagnosis of HZ (International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code 053.xx) in the 90 days prior to January 1, 2011. Subjects contributed person-days to the denominator until the occurrence of one of the following events: end of continuous enrollment in the database, a claim for zoster vaccination, diagnosis of HZ or end of the observation period (December 31, 2011). The numerator was defined as enrollees within the denominator file exhibiting evidence of HZ. Annual IRs were calculated for the entire population in the database as well as by gender and age group; standardized IRs were also produced using the 2010 US Census data.ResultsThe overall annual IR of HZ across all ages was 4.47 per 1000 person-years (95 % confidence interval [CI]: 4.44–4.50) which monotonically increased with age from 0.86 (95 % CI: 0.84–0.88) for those aged ≤19 to 12.78 (95 % CI: 12.49–13.07) for patients ≥80 years. The IR was 8.46 (95 % CI: 8.39–8.52) among adults ≥50 years and 10.46 (95 % CI: 10.35–10.56) among those aged ≥60 years. Women compared to men had higher HZ incidence (5.25, 95 % CI: 5.21–5.29 vs. 3.66, 95 % CI: 3.62–3.69) and this was seen across all age groups. When adjusted for age and gender using 2010 US Census data, the annual IR was 4.63 per 1000 person-years (95 % CI: 4.61–4.66).ConclusionsDespite the availability of a vaccine, HZ remains common among immunocompetent adults in the US with incidence rates of HZ observed to increase with age and be higher in women than men.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-015-1262-8) contains supplementary material, which is available to authorized users.