Are Prescription Drugs Worth the Money?

As prescription drug spending grows, employers — who pay a large part of the bill — want to know if they are getting their money’s worth. A critical review of scientific literature on some common diseases provides the answer.

By Wayne N. Burton, MD, Alan Morrison, PhD, Albert I. Wertheimer, PhD

NOTE: This article is adapted with permission from an article originally published in the June 2003 issue (Volume 45, Issue 6) of the Journal of Occupational and Environmental Medicine

American employers subsidize the bulk of health care for people under the age of 65. Many of those employers wonder whether this is money well spent, especially the dollars that go towards covering the cost of prescription drugs. The question is valid, and answers are scattered through thousands of pages of published research. No single study provides absolute proof, of course, but there is definitely a growing body of evidence that shows a net benefit for employers.

Health economists have calculated the economic impact of many common diseases. These studies divided the costs into direct — the costs of medical treatment, generally including inpatient, outpatient and pharmaceutical costs — and indirect costs — defined here as the cost of lost productivity. Indirect costs predominate for many chronic conditions that intermittently affect work performance but are rarely totally disabling, like migraine, for example.

Pharmaceuticals are effective in treating many of these conditions. The extent to which they also reduce worker productivity losses is important to employers. Evidence of that impact has emerged from research in the past few years. Our critical review of clinical trials and other studies demonstrates that employers can view their health care spending as an investment that can help keep employees healthy and productive on the job. In most cases, the cost of the investment in healthy employees pays off with lower productivity losses.

Methodology and study limitations

We searched three major databases: Medline, International Pharmaceutical Abstracts and the Cochrane Database of Systematic Reviews. We looked for articles published between 1990 and 2002 that described prospective or retrospective studies of pharmaceuticals, included a control (placebo, no treatment or usual therapy) and measured the impact on productivity. We included only articles based on original data rather than pharmacoeconomic models.

We defined productivity loss as a loss of work (or school) time and productivity cost as the monetary value of the productivity loss. We expressed productivity loss in terms of absenteeism and "presenteeism," i.e., time lost because of diminished capacity while at work.

Our search found convincing evidence in the literature of reduction in worker productivity losses caused by illness for over a dozen drug classes. The evidence is particularly extensive for influenza vaccination, triptans for migraine and nonsedating antihistamines for allergies. Much of the evidence relating drug treatment to reduced productivity losses comes from randomized, double blind, placebo-controlled trials and can be accepted as valid.

Although the data is impressive, some caveats are in order. Most studies measure decreased productivity indirectly in terms of loss of work-time. (An exception is the key study of the effects of antihistamines in which the subjects were insurance claims processors whose productivity could be measured directly as the number of claims processed per day.) Furthermore, productivity losses were self-reported in most of the studies we reviewed. Researchers have developed several valuable instruments to quantify self-reported losses, but patients’ estimates of their effectiveness while working with symptoms remain subjective approximations.

Patient reports are most reliable when the period of recall is short. Many studies used daily diaries, and absenteeism recorded in this way is likely to be reliable. In other studies, patients were asked to recall absenteeism for prior periods of weeks or months — a less reliable procedure that tends to produce estimates of longer absences.

In all of the studies, productivity costs were calculated rather than directly observed. These calculations are somewhat speculative because there is disagreement about their theoretical underpinnings. In addition, calculations for specific groups of employees cannot necessarily be generalized: Like politics, all productivity costs are local.

Finally, the reductions in lost productivity reviewed here may strike some readers as relatively small increments. Bear in mind, though, that all represent statistically significant differences and that their impact is potentially enormous when applied to the thousands of people affected by the diseases we have considered. Clearly, the costs of some classes of medications may best be viewed as an investment in the improved health and productivity of the workforce.

To review the data on a specific disease, please make a selection from the "Jump to . . ." section at the top of this page.

Allergies

Antihistamines are used to treat the symptoms of allergies, including allergic rhinitis and hives. In the former, productivity is lowered both by the condition and by its treatment with over-the-counter medications that, until very recently, had sedating side effects. Comparative studies have shown that nonsedating antihistamines do not impair cognitive performance or driving proficiency.

A landmark study of claims processors at a large insurance company compared the two types of antihistamines. This retrospective analysis linked data sets containing pharmaceutical claims and daily work output records. Employees who used sedating antihistamines processed an average 8 percent fewer claims than usual in the three days after treatment began. Those who used nonsedating antihistamines experienced an average 5 percent increase in their output. The 13 percent net difference was statistically significant and economically valuable.

The nonsedating antihistamine, fexofenadine, was tested against placebo in a two-week randomized, double-blind trial among patients with seasonal allergic rhinitis. A self-administered questionnaire, the Work Productivity and Activity Impairment instrument, measured time missed and reduced performance at work. Overall impairment decreased between 7 and 9 percent among those receiving medication, depending on the strength of the dose, compared with a 2 percent decrease in the placebo group. Comparable results were obtained in two similarly designed trials at lower doses.

The allergy studies

A closer look at allergies. Asthma and Allergy Foundation of America and the National Pharmaceutical Council; 2001.

Burton WN, Conti DJ, Chen CY, Schultz AB, Edington DW. The impact of allergies and allergy treatment on worker productivity. J Occup Environ Med. 2001;43:64-71.

Cockburn IM, Bailit HL, Berndt ER, Finkelstein SN. Loss of work productivity due to illness and medical treatment. J Occup Environ Med. 1999;41:948-953.

Crystal-Peters J, Crown WH, Goetzel RZ, Schutt DC. The cost of productivity losses associated with allergic rhinitis. Am J Manage Care. 2000;6:373-378.

Kay GG, Berman B, Mockoviak SH, et al. Initial and steady-state effects of diphenhydramine and loratadine on sedation, cognition, mood, and psychomotor performance. Arch Intern Med. 1997; 157:2350-2356.

Meltzer EO, Casale TB, Nathan RA, Thompson AK. Once-daily fexofenadine HCl improves quality of life and reduces work and activity impairment in patients with seasonal allergic rhinitis. Ann Allergy Asthma Immunol. 1999;83:311-317.

Reilly MC, Tanner A, Meltzer EO. Work, classroom and activity impairment instruments. Validation studies in allergic rhinitis. Clin Drug Invest. 1996;11:278-288.

Reilly MC, Zbrozek AS, Dukes EM. The validity and reproducibility of a work productivity and activity impairment instrument. Pharmacoeconomics. 1993;4: 353-365.

Tanner LA, Reilly M, Meltzer EO, Bradford JE, Mason J. Effect of fexofenadine HCl on quality of life and work, classroom, and daily activity impairment in patients with seasonal allergic rhinitis. Am J Managed Care 1999;5(Suppl): S235-S247.

Weiler JM, Bloomfield JR, Woodworth GG, et al. Effects of fexofenadine, diphenhydramine, and alcohol on driving performance. A randomized, placebo controlled trial in the Iowa driving simulator. Ann Intern Med. 2000;132:354-363.

Asthma

The impact of antiasthma agents on productivity losses has received surprisingly little study, given the extent of losses attributed to asthma and the central importance of drug treatment. The effect of an inhaled beta-agonist on productivity was tested in an open-label, single group, pretest-posttest trial. Based on daily diaries, the number of work or school days missed due to asthma decreased by 57 percent over the course of four weeks.

Leukotriene receptor antagonists, a relatively new class of antiasthma drugs, were tested in a 13-week trial. Patients who received the medication missed an average 0.16 days per month from work or school, less than half the 0.35 days for those treated with placebo.

The asthma studies

Northfield M, Patel RK, Richardson A, Taylor MD, Richardson PD. Lifestyle changes in mild asthma during intermittent symptom-related use of terbutaline inhaled via ‘Turbohaler’. Curr Med Res Opin. 1991;12:441-449.

Smith DH, Malone DC, Lawson KA, Okamoto LJ, Battista C, Saunders WB. A national estimate of the economic costs of asthma. Am J Respir Crit Care Med.156:787-793, 1997.

Suissa S, Dennis R, Ernst P, Sheehy O, Wood-Dauphinee S. Effectiveness of the leukotriene receptor antagonist zafirlukast for mild-to-moderate asthma: a randomized, double-blind, placebo-controlled trial. Ann Intern Med. 1997; 126:177-183.

Weiss KB, Gergen PJ, Hodgson TA. An economic evaluation of asthma in the United States. N Engl J Med. 1992;326: 862-866.

Depression

Traditional antidepressants have been largely superseded by selective serotonin reuptake inhibitors (SSRIs) and newer compounds, but studies with the older drugs provided the "proof of concept" that antidepressants could reduce work loss. In five separate studies that typically measured work loss in terms of the patient’s work history rather than the number of days lost, a median 45 percent of patients in the antidepressant groups were work-impaired compared with 81 percent in the placebo groups.

The newer SSRIs were compared with tricyclic antidepressants in two retrospective analyses of absenteeism in patients who had been employed at the start of depressive episodes. In the first study 45.3 percent of the patients who were not on antidepressants were absent from work at the time of their office visit compared with 43.6 percent of those receiving tricyclic antidepressants and 26.3 percent of those receiving an SSRI. In the second study, the rate of absenteeism was 70.2 percent among those not treated, 57.7 percent among those treated with tricyclics and 39.8 percent among those treated with the SSRI.

The depression studies

Davidson JR, Giller EL, Zisook S, Overall JE. An efficacy study of isocarboxazid and placebo in depression, and its relationship to depressive nosology. Arch Gen Psychiatry 1988;45:120-127.

Elkin I, Shea MT, Watkins JT, et al. National Institute of Mental Health Treatment of Depression Collaborative Research Program. General effectiveness of treatments. Arch Gen Psychiatry. 1989; 46:971-982; discussion 983.

Giller E Jr, Bialos D, Riddle MA, Waldo MC. MAOI treatment response: multiaxial assessment. J Affect Disord. 1988; 4:171-175.

Jacobs RJ, Davidson JR, Gupta S, Meyerhoff AS. The effects of clonazepam on quality of life and work productivity in panic disorder. Am J Manage Care. 1997; 3:1187-1196.

Mintz J, Mintz LI, Arruda MJ, Hwang SS. Treatments of depression and the functional capacity to work. Arch Gen Psychiatry. 1992;49:761-768.

Quitkin FM, McGrath PJ, Stewart JW, et al. Phenelzine and imipramine in mood reactive depressives. Further delineation of the syndrome of atypical depression. Arch Gen Psychiatry. 1989;46:787-793.

Simon GE, Barber C, Birnbaum HG, et al. Depression and work productivity: the comparative costs of treatment versus nontreatment. J Occup Environ Med. 2001;43:2-9.

Souetre E, Lozet H, Cimarosti I. Predicting factors for absenteeism in patients with major depressive disorders. Eur Epidemiol. 1997;13:87-93.

Stewart JW, Quitkin FM, McGrath PJ, et al. Social functioning in chronic depression: effect of 6 weeks of antidepressant treatment. Psychiatry Res. 1988;25:213-222.

Tollefson GD, Souetre E, Thomander L, Potvin JH. Comorbid anxious signs and symptoms in major depression: impact on functional work capacity and comparative treatment outcomes. Int Clin Psychopharmacol. 1993;8:281-293.

Diabetes mellitus

Diabetes mellitus affects nearly 6 percent of Americans and generates nearly $100 billion in direct and indirect costs annually. At least 8 million Americans are diagnosed with diabetes, but just as many remain undiagnosed. Among those who know they have the disease, up to 800,000 have type 1 diabetes and depend on insulin, while 7 to 7.5 million have type 2, which can be controlled by other medications and diet.

Glipizide, a second-generation sulfonylurea, reduced absenteeism considerably in patients with type 2 diabetes in a 12-week, double-blind, placebo-controlled trial. Days missed from work were nearly five times as common among the placebo group as among those on medication. In addition, 97 percent of the glipizide patient group retained employment during the trial compared with 85 percent in the placebo group. Productivity losses from absenteeism per worker per month were $24 for men in the glipizide group versus $115 in the placebo group.

The diabetes studies

Foster RH, Plosker GL. Glipizide. A review of the pharmacoeconomic implications of the extended-release formulation in type 2 diabetes mellitus. Pharmacoeconomics. 2000;18:289-306.

Musich SA, Burton WN, Edington DE. Costs and benefits of prevention and disease management. Dis Manage Health Outcomes. 1999;5:153-166.

Testa MA, Simonson DC. Health economic benefits and quality of life during improved glycemic control in patients with type 2 diabetes mellitus: a randomized, controlled, double-blind trial. JAMA. 1998;280:1490-1496.

Influenza virus vaccination

The effects of influenza vaccination on symptoms and work loss have been studied intensely in at least eight randomized, controlled trials. Vaccination significantly reduced lost workdays in every study, with the exception of a trial conducted in 1997-1998, when the vaccine used was poorly matched to that season’s flu strains. Excluding this value, the median number of work-loss days per person in the vaccine and control groups was reduced by half — 0.32 days for the vaccine groups vs. 0.63 for the control groups.

Productivity costs were estimated for several of the trials. Nichol et al. reported that productivity costs per employee in the Minneapolis/St. Paul, Minnesota area in 1994 were $5.84 for the 30 minutes it took to vaccinate each worker and $1.87 for side effects vs. $48.57 for work loss avoided by vaccination for a net productivity saving of $40.86. There was also a net saving in direct costs per employee of $10.70 for vaccination and care of side effects compared with $16.68 for care avoided for respiratory illness.

On the other hand, Bridges et al used essentially the same methods in 1998 to compute a net productivity cost among full-time employees of Ford Motor Company in Dearborn, Mich. The cost of lost workdays was $19.40 per employee in the vaccine group and $28.43 in the control group, but the time taken for vaccination was worth $14.70, making the productivity costs greater in the vaccinated group. Similarly, the direct costs of influenza-like illness were $6.22 in the vaccine group and $9.71 in the control group, but this was offset by the $10 cost of the vaccination.

The difference in the economic outcomes might be related to the severity of the influenza and/or the propensity of employees to be absent: Flu-related absence in the placebo group — and, hence, the potential for reduction in productivity costs — was considerably greater in the Minneapolis trial.

Vaccination was cost-saving in the two case-control studies. In the first, productivity costs at a nuclear facility in Washington state were estimated to be $38.12 lower per vaccinated employee than per unvaccinated employee. Direct costs were also lower in the vaccinated group. In the study by Campbell et al reported savings in lost productivity due to influenza was $37.78 per vaccinated employee at a North Carolina textile corporation. This exceeded the $22.13 cost of vaccination (which included contacting employees, supplies and medical staff).

Two other trials among children showed that vaccination reduced school absences — and thus, we might add, the need for working parents to take days off. During the five months of the 1995-1996 season, unvaccinated preschool children were absent an average 2.3 days compared with only 0.5 days for vaccinated children. In a trial of two different vaccines among Russian schoolchildren, the risk of school absence because of respiratory illness during the peak flu season was reduced by 56 percent with a U.S. inactivated split-virus vaccine and by 47 percent with a Russian live, attenuated virus vaccine.

The flu vaccine studies

Bridges CB, Thompson WW, Meltzer MI, et al. Effectiveness and cost-benefit of influenza vaccination of healthy working adults: a randomized controlled trial. JAMA. 2000;284:1655-1663.

Campbell DS, Rumley MH. Cost effectiveness of the influenza vaccine in a healthy, working-age population. J Occup Environ Med. 1997;39:408-414.

Colombo C, Argiolas L, La Vecchia C, Negri E, Meloni G, Meloni T. Influenza vaccine in healthy preschool children. Rev Epidemiol Sante Publique. 2001;49: 157-162.

Dille JH. A worksite influenza immunization program. Impact on lost work days, health care utilization, and health care spending. AAOHN J. 1999;47:301-309.

Khan AS, Polezhaev F, Vasiljeva R, et al. Comparison of US inactivated split-virus and Russian live attenuated, cold-adapted trivalent influenza vaccines in Russian schoolchildren. J Infect Dis. 1996;173: 453-456.

Nichol KL, Lind A, Margolis KL, et al. The effectiveness of vaccination against influenza in healthy, working adults. N Engl J Med. 1995;333:889-893.

Nichol KL, Mendelman PM, Mallon KP, et al. Effectiveness of live, attenuated intranasal influenza virus vaccine in healthy, working adults: a randomized controlled trial. JAMA. 1999;282:137-144.

Saxen H, Virtanen M. Randomized, placebo-controlled double blind study on the efficacy of influenza immunization on absenteeism of health care workers. Pediatr Infect Dis J. 1999;18:779-783.

Wilde JA, McMillan JA, Serwint J, Butta J, O’Riordan MA, Steinhoff MC. Effectiveness of influenza vaccine in health care professionals: a randomized trial. JAMA. 1999;281:908-913.

Respiratory infection

Common respiratory infections (including acute bronchitis, sore throat, pneumonia and influenza) cost employers well over $100 billion a year, a third of that in work absences. Depending on the condition, they are treated with antibiotics, antivirals or not at all. (It’s important to remember that treating a viral disease like influenza with an antibiotic is a useless endeavor.)

Two well-designed trials at primary care centers in North Carolina measured the impact on work loss when antibiotics are used to treat respiratory infection. Patients with bronchitis who were treated with erythromycin missed an average 0.81 days of work compared with 2.16 days for patients on placebo. In contrast, antibiotic treatment of sore throat did not reduce work loss among U.K. residents. This was not surprising because antibiotics had little impact on symptoms.

Zanamivir and oseltamivir are antivirals that can be used to treat patients who have already developed flu symptoms. During the 1994-95 season, a study conducted in 14 countries throughout Europe and North America measured the effect of a five-day course of inhaled zanamivir on absenteeism in people who’d had flu for less than two days. Workers in the placebo group missed an average of 3.3 days by the day 6 visit, compared with 2.5 to 2.8 days, depending on the dose, for workers treated with zanamivir.

A number of other studies measured time to return to normal activities rather than work loss. In general, people who received drug therapy were feeling up to snuff in six days rather than seven for those who were not treated.

The respiratory infection studies

Aoki FY, Fleming DM, Griffin AD, Lacey LA, Edmundson S. Impact of zanamivir treatment on productivity, health status and healthcare resource use in patients with influenza. Zanamivir Study Group. Pharmacoeconomics. 2000;17:187-195.

Birnbaum HG, Morley M, Greenberg PE, Colice GL. Economic burden of respiratory infections in an employed population. Chest. 2002;122:603-611.

Burls A, Clark W, Stewart T, et al. Zanamivir for the treatment of influenza in adults: a systematic review and economic evaluation. Health Technol Assess.2002;6:1-87.

King DE, Williams WC, Bishop L, Shechter A. Effectiveness of erythromycin in the treatment of acute bronchitis. J Fam Pract. 1996;42:601-605.

Little P, Williamson I, Warner G, Gould C, Gantley M, Kinmonth AL. Open randomized trial of prescribing strategies in managing sore throat. BMJ. 1997;314: 722-727.

Monto AS, Webster A, Keene O. Randomized, placebo-controlled studies of inhaled zanamivir in the treatment of influenza A and B: pooled efficacy analysis. J Antimicrob Chemother. 1999; 44(Suppl B):23-29.

Treanor JJ, Hayden FG, Vrooman PS, et al. Efficacy and safety of the oral neuraminidase inhibitor oseltamivir in treating acute influenza: a randomized controlled trial. US Oral Neuraminidase Study Group. JAMA. 2000;283:1016-1024.

Welliver R, Monto AS, Carewicz O, et al. Effectiveness of oseltamivir in preventing influenza in household contacts: a randomized controlled trial. JAMA. 2001; 285:748-754.

Migraine

Triptans (serotonin receptor agonists) are a relatively new class of drugs for migraine headaches, but their effects on productivity loss have been studied quite intensively. Randomized controlled trials have established the efficacy of triptans in reducing productivity losses at work. Pretest—posttest studies have determined losses in more naturalistic settings. The results of both types of trials are largely consistent.

In a group of five randomized, controlled trials of injected and oral triptans, patients estimated and recorded their work absences and reduced efficiency as they experienced each attack. While results of the five trials varied, the difference between the triptan and control groups in average time lost was always statistically significant. The median time saved per migraine attack by using a triptan was 0.64 hours for absenteeism, 0.6 hours for presenteeism and 1.1 hour total.

Another group of nine trials compared the average days of productivity loss per patient per month when subjects used their usual therapy for migraine attacks, with productivity loss when subjects used sumatriptan. Each phase typically lasted three to 12 months. Productivity losses were lower in the sumatriptan phase in every trial, although there was considerable variation in the results. The median days of productivity loss per patient per month for all nine trials was 1.69 days with patients’ usual therapy and 0.67 days with sumatriptan.

The migraine studies

Adelman JU, Sharfman M, Johnson R, et al. Impact of oral sumatriptan on workplace productivity, health-related quality of life, healthcare use, and patient satisfaction with medication in nurses with migraine. Am J Manage Care. 1996;2:1407-1416.

Burton WN, Conti DJ, Chen CY, Schultz AB, Edington DW. The economic burden of lost productivity due to migraine headache: a specific worksite analysis. J Occup Environ Med. 2002;44:523-529.

Cady RC, Ryan R, Jhingran P, O’Quinn S, Pait DG. Sumatriptan injection reduces productivity loss during a migraine attack: results of a double blind, placebo-controlled trial. Arch Intern Med. 1998; 158:1013-1018.

Cohen JA, Beall D, Beck A, et al. Sumatriptan treatment for migraine in a health maintenance organization: economic, humanistic, and clinical outcomes. Clin Ther. 1999;21:190-204.

Cortelli P, Dahlof C, Bouchard J, et al. A multinational investigation of the impact of subcutaneous sumatriptan. III: Workplace productivity and non-workplace activity. Pharmacoeconomics. 1997; 11(Suppl 1):35-42.

Dahlof CG. Health-related quality of life under six months’ treatment of migraine —an open clinic-based longitudinal study. Cephalalgia 1995;15:414-422; discussion 336.

Dasbach EJ, Carides GW, Gerth WC, Santanello NC, Pigeon JG, Kramer. Work and productivity loss in the rizatriptan multiple attack study. Cephalalgia. 2000;20:830-834.

Davies GM, Santanello N, Gerth W, Lerner D, Block GA. Validation of a migraine work and productivity loss questionnaire for use in migraine studies. Cephalalgia. 1999;19:497-502.

Gross ML, Dowson AJ, Deavy L, Duthie T. Impact of oral sumatriptan 50 mg on work productivity and quality of life in migraineurs. Br J Med Econ. 1996;10: 231-246.

Jhingran P, Cady RK, Rubino J, Miller D, Grice RB, Gutterman DL. Improvements in health-related quality of life with sumatriptan treatment for migraine. J Fam Pract .1996;42:36-42.

Laloux P, Vakaet A, Monseu G, Jacquy J, Bourgeois P, van der Linden C. Subcutaneous sumatriptan compared with usual acute treatments for migraine: clinical and pharmacoeconomic evaluation. Acta Neurol Belg. 1998;98:332-341.

Larbig W, Bruggenjurgen B. Work productivity and resource consumption among migraineurs under current treatment and during treatment with sumatriptan: an economic evaluation of acute treatment in moderate to severe migraineurs. Headache Quart Curr Trea Res. 1997;8:237-246.

Legg RF, Sclar DA, Nemec NL, Tarnai J, Mackowiak JI. Cost-effectiveness of sumatriptan in a managed care population. Am J Manage Care. 1997;3:117-122.

Lofland JH, Johnson NE, Batenhorst AS, Nash DB. Changes in resource use and outcomes for patients with migraine treated with sumatriptan: a managed care perspective. Arch Intern Med. 1999;159: 857-863.

Lofland JH, Locklear JC, Frick KD. Different approaches to valuing the lost productivity of patients with migraine. Pharmacoeconomics. 2001;19:917-925.

Schulman EA, Cady RK, Henry D, et al. Effectiveness of sumatriptan in reducing productivity loss due to migraine: results of a randomized, double-blind, placebo-controlled clinical trial. Mayo Clin Proc.2000;75:782-789.

Solomon GD, Santanello N. Impact of migraine and migraine therapy on productivity and quality of life. Neurology 2000;55(9 Suppl 2):S29-S35.

Stang P, Cady R, Batenhorst A, Hoffman L. Workplace productivity. A review of the impact of migraine and its treatment. Pharmacoeconomics. 2001;19:231-244.

Other important studies

Brouwer WB, Koopmanschap MA. How to calculate indirect costs in economic evaluations. Pharmacoeconomics. 1998; 13:563-569.

Burton WN, Conti DJ, Chen CY, Schultz AB, Edington DW. The role of health risk factors and disease on worker productivity. J Occup Environ Med. 1999; 41:863-877.

Goetzel RZ, Ozminkowski RJ, MeneadesL, Stewart M, Schutt DC. Pharmaceuticals — cost or investment? An Employer’s Perspective. J Occup Environ Med 2000;42:338-351.

Heaney CA, Goetzel RZ. A review of health-related outcomes of multi-component worksite health promotion programs. Am J Health Promot. 1997;11: 290-307.

Koopmanschap MA, Rutten FFH, van Ineveld BM, van Roijen L. The friction cost method for measuring indirect costs of disease. J Health Econ. 1995;14:171-189.

Koopmanschap MA, van Ineveld BM. Towards a new approach for estimating indirect costs of disease. Soc Sci Med. 1992;34:1005-1010.

Liljas B. How to calculate indirect costs in economic evaluations. Pharmacoeconomics.1998;13:1-7.

McCunney RJ. Health and productivity: a role for occupational health professionals. J Occup Environ Med. 2001;43:30-35.

Measuring Employee Productivity: A Guide to Self-Assessment Tools. Glen Allen, VA: Institute for Health & Productivity Management; 2001.

Petitti DB. Meta-Analysis, Decision Analysis, and Cost-Effectiveness Analysis. Methods for Quantitative Synthesis in Medicine. Monographs in Epidemiology and Biostatistics, Volume 24. New York: Oxford University Press; 1994.

Wayne Burton is Corporate Medical Director of Bank One in Chicago and a longtime contributor to Business & Health (wayne_n_burtonmd@bankone.com). Alan Morrison is a Research Associate and Albert Wertheimer is Director of the Center for Pharmaceutical Health Services Research at the School of Pharmacy, Temple University, Philadelphia.

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