Elsevier

The Spine Journal

Volume 8, Issue 1, January–February 2008, Pages 8-20
The Spine Journal

Introduction
A systematic review of low back pain cost of illness studies in the United States and internationally

https://doi.org/10.1016/j.spinee.2007.10.005Get rights and content

Abstract

Background context

The economic burden of low back pain (LBP) is very large and appears to be growing. It is not possible to impact this burden without understanding the strengths and weaknesses of the research on which these costs are calculated.

Purpose

To conduct a systematic review of LBP cost of illness studies in the United States and internationally.

Study design/setting

Systematic review of the literature.

Methods

Medline was searched to uncover studies about the direct or indirect costs of LBP published in English from 1997 to 2007. Data extracted for each eligible study included study design, population, definition of LBP, methods of estimating costs, year of data, and estimates of direct, indirect, or total costs. Results were synthesized descriptively.

Results

The search yielded 147 studies, of which 21 were deemed relevant; 4 other studies and 2 additional abstracts were found by searching reference lists, bringing the total to 27 relevant studies. The studies reported on data from Australia, Belgium, Japan, Korea, the Netherlands, Sweden, the UK, and the United States. Nine studies estimated direct costs only, nine indirect costs only, and nine both direct and indirect costs, from a societal (n=18) or private insurer (n=9) perspective. Methodology used to derive both direct and indirect cost estimates differed markedly among the studies. Among studies providing a breakdown on direct costs, the largest proportion of direct medical costs for LBP was spent on physical therapy (17%) and inpatient services (17%), followed by pharmacy (13%) and primary care (13%). Among studies providing estimates of total costs, indirect costs resulting from lost work productivity represented a majority of overall costs associated with LBP. Three studies reported that estimates with the friction period approach were 56% lower than with the human capital approach.

Conclusions

Several studies have attempted to estimate the direct, indirect, or total costs associated with LBP in various countries using heterogeneous methodology. Estimates of the economic costs in different countries vary greatly depending on study methodology but by any standards must be considered a substantial burden on society. This review did not identify any studies estimating the total costs of LBP in the United States from a societal perspective. Such studies may be helpful in determining appropriate allocation of health-care resources devoted to this condition.

Introduction

The focus of this special focus issue of The Spine Journal is on the management of chronic low back pain (CLBP). This topic was chosen partly because of its imposing socioeconomic burden, which appears to be increasing rapidly despite technological advances in diagnosis and the introduction of numerous interventions in recent years. The general pessimism surrounding the prognosis of CLBP is such that few clinicians, researchers, or third-party payers would dispute any proposed cost estimate, no matter how large it may appear. Such views are understandable when faced with a prevalent, disabling, clinically challenging, and seemingly expensive condition such as CLBP. However, it is essential to understand the precise magnitude of the economic burden of CLBP before examining potential cost-saving solutions or comparing the cost effectiveness of competing interventions. This can be achieved by reviewing cost of illness studies.

Cost of illness studies summarizing the economic burden of a particular disease must be considered by all stakeholders, including patients, clinicians, and third-party payers when deciding on the allocation of scarce health-care resources [1]. It should be noted that cost of illness studies serves a different purpose than health economic evaluations (eg, cost-benefit analysis, cost-effectiveness analysis, cost-utility analysis), which are focused on evaluating the costs of interventions rather than estimating the cost of a particular disease [1]. The purpose of this study was to conduct a systematic review of CLBP cost of illness estimates in the United States and internationally. To help readers understand some of the basic principles of health economics pertinent to the studies summarized in this review, a brief overview of important concepts related to cost of illness studies is presented below.

The economic burden of a disease is the sum of all costs associated with that condition which would not otherwise be incurred if that disease did not exist. Given the many categories of costs that must be considered, it can be challenging to fully estimate the economic burden of an illness as data are often unavailable. The term “cost” in health economics refers to the value of the consequences of using a particular good or service rather than its price. That value corresponds to the best alternative use of those resources, which is termed the opportunity cost. The difference between cost and price can be demonstrated by comparing what a clinician charges for his services versus the amount actually reimbursed for those services; the latter may be a better proxy of true cost than the former. Despite this example, it should be made clear that estimating the economic burden of a disease is not simply a matter of tabulating the amount reimbursed for all clinician services related to a particular diagnosis. The total cost of illness—or economic burden—has three components: (1) direct (medical and nonmedical) costs; (2) indirect costs; and (3) intangible costs.

Direct costs refer to those that, at least in principle, involve a monetary exchange. Direct medical costs are most familiar to readers and commonly include costs incurred for physician services, medical devices, medications, hospital services, diagnostic testing, etc [2]. The term direct health-care costs may be more accurate because allied health, complementary and alternative medicine (CAM), and other nonphysician costs are included. Direct medical costs are typically the easiest to estimate because records are kept of such transactions by clinicians, third-party payers, employers, or patients.

Direct nonmedical costs are those related to goods and services consumed directly because of the illness but which are not considered to be health care related. They include, for example, transportation or other travel costs to attend medical appointments, meals eaten outside the home when receiving health care, renovations to make a house more accessible for those who may become physically disabled secondary to a disease, and so on. These expenses are easy to overlook when considering the economic burden of a disease but can constitute an important source of related costs.

Indirect costs are those reflecting the economic value of consequences for which there is no direct monetary transfer. They commonly include costs related to employment and household productivity. Employment costs include both work absences resulting in foregone productivity (termed “absenteeism”) and decreased productivity for those who continue to work despite being affected by their condition (termed “presenteeism”) [3]. Indirect costs are often more difficult to measure than direct costs. For example, it is nearly impossible to determine whether presenteeism is in fact occurring and which medical condition, if any, is primarily responsible for its occurrence. Such productivity losses can be estimated by interviewing workers and asking them to evaluate their own reduced productivity as it relates to their health status, or by interviewing their supervisors and asking for their opinions about whether a particular worker's productivity has changed secondary to a disease. Rarely can such presenteeism costs be measured objectively or with certainty. Absenteeism costs are generally easier to estimate because employer records and workers' compensation insurance systems will note health-related work absences.

There is debate among economists about the preferred methods for estimating indirect costs, the majority of which are often composed of lost productivity [3]. The most common method is the human capital approach, which assumes that the economic value of an employee's productivity is equal to the cost of their salary and benefits [4]. Lost productivity is therefore estimated by calculating earnings lost during work absences, regardless of the length of absence. This method would therefore calculate lost productivity for disability-related early retirement as the value of lost earnings from the date of disability until that worker would have reached normal retirement age (eg, 65 y). Employers, however, will eventually replace those employees that are absent for extended periods and regain the value of the original employee's lost productivity. Thus, productivity losses are truly only incurred from the worker's absence for health reasons until a replacement worker is hired, trained, and has reached the productivity of the disabled employee. The length of time required for this transition to occur has been termed the friction period and varies for different industries and economic conditions based on factors that may influence the time required to replace an employee (eg, unemployment level, job skill and education requirements, and location) [5]. Evaluating the cost of lost productivity with this assumption has been termed the friction cost approach [4]. Alternatively, the cost of hiring replacement workers for employees on disability leave may also be used to estimate lost productivity [3]. A combination of methods may be most appropriate to estimate indirect costs by, for example, using the human capital approach for temporary productivity losses from absences that are shorter than the friction period, and using the friction cost approach for longer-term productivity losses.

In addition to lost work productivity, individuals with an illness may also incur productivity losses at home if they are unable to complete routine household tasks (eg, cleaning, cooking, and maintenance). This is true whether they must rely on paid outsiders to complete such tasks on their behalf, or whether unpaid household members must do so. These indirect costs can be estimated using the earnings of a hired household worker or by using an estimate of the national or regional value of leisure time, which is typically less than the mean hourly wage.

The third type of cost that may be considered when estimating the total cost of illness for a particular disease is termed intangible costs. These costs reflect the value of decreased enjoyment of life because of illness. However, these costs are rarely included when estimating the economic burden of an illness because of general societal discomfort with placing a monetary value on these aspects of a disease.

The cost of an illness may be viewed from various perspectives and depends on who bears the costs. Costs could be estimated from a patient perspective (eg, out-of-pocket costs), employer perspective (eg, cost of worker's compensation insurance premiums and lost productivity), insurance company perspective (eg, cost of claims paid), government perspective (eg, cost of public health services), or societal perspective, which would include all related costs. The latter is the most comprehensive and broadest perspective and avoids underestimating costs when only considered from a narrower perspective.

The perspective chosen will also impact the types and sources of data used in the cost of illness study. Employer, insurer, or government perspective may derive acceptable cost estimates by apportioning claims in large utilization databases to specific diagnoses, which has been termed a top-down approach [4]. Alternatively, the patient perspective may extrapolate costs from interviews or diaries about health-care utilization and costs, which has been termed a bottom-up approach [4]. The societal perspective could combine both approaches to capture more data.

Section snippets

Methods

A search of Medline was conducted on July 1, 2007, for studies pertaining to the costs of low back pain (LBP) using the following strategy:

  • 1.

    *Back Pain/Economics

  • 2.

    low back pain.mp. or exp Low Back Pain/

  • 3.

    health care costs.mp. or exp Health Care Costs/

  • 4.

    cost of illness.mp. or exp Cost of Illness/

  • 5.

    health expenditures.mp. or exp health expenditures/

  • 6.

    exp Health Resources/Economics, Utilization

  • 7.

    exp Sick Leave/Economics

  • 8.

    1 or (2 and (or/3-7))

The search was limited to studies published in English from 1997 to 2007

Results

The search strategy yielded 147 studies, of which 12 (8%) were relevant, 114 (78%) were irrelevant because they did not meet eligibility criteria, and 21 (14%) were of uncertain relevance based on information contained in the search records (eg, title, abstract). When full-text articles were retrieved for the latter group, an additional eight studies were deemed relevant; five additional studies were also located by searching references of the studies obtained via Medline. In addition, two

Discussion

Numerous LBP cost of illness studies were identified in this review and provided valuable information for readers to understand the magnitude of its economic burden from different perspectives in various countries. Despite differences in study methods producing a wide range of cost of illness estimates, it was apparent that LBP represents an important economic burden wherever it was studied. One of the most notable findings in this review is that the methodology used to derive LBP cost of

Conclusion

This review identified several studies that have previously attempted to estimate the direct, indirect, or total costs associated with LBP, both in the United States and internationally. Study methodology differed considerably, making direct cost comparisons across studies and between countries difficult. The largest components of direct medical costs were PT, inpatient services, pharmacy, and primary care. From studies conducted outside the United States, it appears that direct medical costs

References (30)

  • E.K. Hansson et al.

    The costs for persons sick-listed more than one month because of low back or neck problems. A two-year prospective study of Swedish patients

    Eur Spine J

    (2005)
  • Z.J. Van et al.

    Low back pain: from algorithm to cost-effectiveness?

    Pain Pract

    (2005)
  • P.J. Watson et al.

    Medically certified work loss, recurrence and costs of wage compensation for back pain: a follow-up study of the working population of Jersey

    Br J Rheumatol

    (1998)
  • S. Shinohara et al.

    Prognosis of accidental low back pain at work

    Tohoku J Exp Med

    (1998 Dec)
  • H.S. Kim et al.

    Treatment duration and cost of work-related low back pain in Korea

    J Korean Med Sci

    (2005)
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