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Contents lists available at ScienceDirect

NeuroToxicology

Cost of detecting a chronic solvent encephalopathy case by screening Heidi Furu a,*, Markku Sainio b, Guy Ahonen b, Hanna Kaisa Hyva¨rinen b, Ari Kaukiainen c a

Finnish Institute of Occupational Health and Doctagon Oy, Finland Finnish Institute of Occupational Health, Finland c Finnish Institute of Occupational Health and The LocalTapiola Group, Finland b

A R T I C L E I N F O

A B S T R A C T

Article history: Received 19 June 2013 Received in revised form 15 December 2013 Accepted 30 December 2013 Available online xxx

Background: Stepwise screening of chronic solvent encephalopathy (CSE), using a postal survey followed by clinical examinations, has been shown to detect symptomatic exposed workers with an occupational disease even in industrialized countries with long-term, but relatively low dose exposure. Previous studies have suggested under-detection and late recognition of CSE, when work ability is already markedly reduced. Aims: The aim was to estimate the cost of detecting one new CSE case by screening and diagnostics, to estimate the career extension needed to cover the cost of screening, and to study the work ability of the CSE cases. Methods: A financial analysis of stepwise postal CSE screening followed by clinical examinations (SPC screening) was carried out, and the results were compared to those of the group of CSE cases referred to the Finnish Institute of Occupational Health (FIOH) by the existing national practice of occupational health services (OHS screening). The work ability of the SPC screened CSE cases was studied in relation to the retirement rate and the Work Ability Index (WAI). Results: An analysis of the costs of detecting a new verified CSE case revealed them to be approximately 16,500 USD. Using the mean monthly wages in the fields concerned, we showed that if a worker is able to continue working for four months longer, the screening covers these costs. The cost for detecting a CSE case was twenty times higher with the existing OHS routine, when actualized according to the national guidelines. A CSE case detected at an early stage enables occupational rehabilitation or measures to decrease solvent exposure. The retirement rate of the SPC screened CSE cases was significantly lower than that of the OHS screened cases (6.7% vs. 74%). The results suggest that SPC screening detects patients at an earlier stage of the disease, when they are still capable of working. Their WAI sores were nevertheless lower than those of the general population, implying a greater risk of becoming excluded from the labor market. Conclusion: Stepwise screening of CSE using a postal survey followed by clinical examinations detected new CSE cases at lower costs than existing OHS screening routines. Detecting CSE at an early stage prevents early retirement. ß 2014 Elsevier Inc. All rights reserved.

Keywords: Encephalopathy Solvent Screening Cost analysis Occupational disease Neurotoxic symptom

1. Introduction 1.1. Solvents Organic solvents are widely used in global industries: in manufacturing and in the thinning of paints, inks, lacquers and glues; in metal de-greasing; and as raw-material in various

industrial sectors. The global solvent market is expected to grow by 2.5% annually and to reach 19.9 million metric tons by 2015, due to dynamic economic development in emerging markets such as China, India, Brazil, and Russia. Thus, millions of workers are occupationally exposed to solvents every year (Wildes, 2007; Solvents: A Global Strategic Business Report, 2010; Market Study: Solvents, 2012). 1.2. Chronic solvent encephalopathy

* Corresponding author at: Finnish Institute of Occupational Health, Doctagon Oy, Laajalahdentie 23, FI-00330 Helsinki, Finland. Tel.: +358 44 755 2032;

Long term exposure to solvents, even at low levels, can lead to permanent adverse effects on the central nervous system, i.e.

http://dx.doi.org/10.1016/j.neuro.2013.12.013 0161-813X/ß 2014 Elsevier Inc. All rights reserved.

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chronic solvent encephalopathy (CSE). This is characterized by disturbances in the working memory, concentration and learning ability (White and Proctor, 1997; Song-Yen et al., 1997; Xiao and Levin, 2000; Akila et al., 2006; Dick, 2006; Kaukiainen et al., 2009a; Keski-Sa¨ntti et al., 2010). There is no treatment for CSE, but the condition no longer seems to progress when exposure ceases (van Valen et al., 2009). The occupations in which CSE is most prevalent are industrial and construction painting, printing press work, floor layering, boat building and other reinforced plastic laminating (Dryson and Ogden, 1998; Saddik et al., 2003; Leira et al., 2006; Keski-Sa¨ntti et al., 2010; Kim and Kang, 2010, www.occupationaldiseases.nl). However, the nationally reported occurrence of CSE varies considerably. This is more likely due to under-detection of CSE, differences in national legislation, and in some cases a lack of primary health care or occupational health services, than to diagnostic criteria or amounts of solvents used (Triebig and Hallermann, 2001; van der Hoek et al., 2001). Paradoxically, the highest numbers of cases are in industrialized countries, i.e. the Nordic countries and the Netherlands, where occupational hygiene is advanced and exposure levels have declined. In contrast, in developing countries, where solvents are abundantly used and occupational hygiene is insufficient, only a few cases have been reported (Dryson and Ogden, 1998; Myers et al., 1999; Triebig and Hallermann, 2001; Saddik et al., 2003; Leira et al., 2006; Misra and Kalita, 2009; Kim et al., 2010; Kim and Kang, 2010; Furu et al., 2012; Spee et al., 2012, www.occupationaldiseases.nl). 1.3. CSE and work ability The majority of CSE patients become excluded from the labor market due to disability pensions or long-term sick leave (Gregersen et al., 1987; Mikkelsen, 1997; van Valen et al., 2009). In a recent study on the work ability of diagnosed CSE cases carried out in Finland, 74% were considered disabled for any work already at the time of diagnosis, and after one year follow-up, only 1 out of 19 was able to continue working, while the rest (95%) ended up on disability pension due to CSE (Keski-Sa¨ntti et al., 2010). This suggests that CSE is usually diagnosed so late that work ability is already strongly affected. Cognitive CSE symptoms, such as difficulties with learning, memory and concentration, limit the possibilities for vocational retraining or re-employment in non-solvent occupations. 1.4. Screening of CSE in working populations In Finland, occupational health services (OHS) are mandatory (Finnish government decree 1485/2001), as are regular health checks for abundantly solvent-exposed workers every three years at the beginning of their careers, and then after 10 years of exposure every one to two years (Sainio et al., 2006). To survey the neurotoxic symptoms, the Euroquest (EQ) questionnaire (Chouanie`re et al., 1997; Carter et al., 2002; Karlson et al., 2000; Williamson, 2007; Kaukiainen et al., 2009b) is recommended. The health check also assesses solvent exposure, other diseases and liver function tests. When CSE-compatible symptoms are encountered with significant long-term exposure, possible differential diagnostic conditions are ruled out by OHS. In the case of a suspected occupational disease, workers are referred to Finnish Institute of Occupational Health (FIOH) for further examinations. These examinations are covered by statutory accident insurance; all employers are obliged to insure their employees. Despite mandatory health checks, it seems that CSE is underdetected in Finland (Kaukiainen et al., 2009a; Furu et al., 2012). Since loss of work ability is strongly associated with CSE (van Valen et al., 2009; Keski-Sa¨ntti et al., 2010), it is crucial to create methods to detect patients in the early stages of the disease and cease

solvent exposure to prevent progression. Although postal surveys lack specificity, they have proven to be an effective way in which to reach and detect symptomatic workers, also in industrialized countries with low dose exposure levels. To determine CSE as an occupational disease, postal surveys should be followed by clinical examinations (Hooisma et al., 1994; Kaukiainen et al., 2009a; Furu et al., 2012; Spee et al., 2012). 1.5. Aims of the study The aim was to estimate the cost of detecting one new CSE case by screening and diagnostics, to estimate the career extension needed to cover the cost of screening, and to study the work ability of the CSE cases. 2. Methods 2.1. Study population and CSE screening routines The current setting used the material of our previous study, in which CSE risk occupations were screened stepwise using a postal questionnaire followed by clinical examinations of symptomatic workers (Furu et al., 2012). For comparison, we examined an existing national OHS standard for screening and diagnosing CSE, based on FIOH material described by Keski-Sa¨ntti et al. (2010). In the stepwise CSE screening using a postal survey followed by clinical examinations (later called stepwise postal-clinical screening, SPC screening), trade union and municipal occupational health unit registers were used to select the solvent-exposed workers. The postal survey consisted of 3640 workers and was directed at the fields with the greatest CSE risk, i.e. industrial and construction painting, floor layering, the printing press industry, boat construction, and the reinforced plastic lamination and metal industries. In Finland, about 20,000 workers of the 2.5 million workforce are abundantly exposed to solvents (Tossavainen and Jaakkola, 1994; Tuomi and Ahonen, 2010), and this sample covered approximately 18% of these. The survey received 1730 responses (48%). This was followed by a clinical examination of subjects fulfilling the criteria, with methods applicable to OHS: CSE symptoms by Euroquest, adequate solvent exposure and no obvious differential diagnostic explanation for the symptoms. All in all, 129 subjects fulfilled all the criteria, of which 83 participated in clinical examinations. Thirty two new CSE suspected cases were found and sent to FIOH for examinations for an occupational disease (Furu et al., 2012). To date, 15 new occupational CSE cases have been detected, and the differential diagnostics are still pending in five cases. These cases are not included in the present study material, but their retirement status and work ability are known. Keski-Sa¨ntti et al. described all the CSE patients referred to FIOH between 2002 and 2004 (2010). They represent CSE cases detected by the existing national OHS screening routine (later called OHS screening) over a three year period. OHS health checks are recommended at one- to three-year intervals, and thus, all 20,000 highly exposed workers should have been checked by OHS at least once during this time. The CSE cases detected by the SPC screening were slightly older than those detected by OHS screening, 57.5 years (44.7–62.6 years) vs. 56.8 years (51.7–60.1 years), respectively. The solvent exposure of the SPC group in years was somewhat higher 38.9 (19–47) years than that of the OHS group, which was 34.0 (10–42) years. However, the solvent exposure in occupational exposure years (OELY) (which is an index of life-time exposure that takes into account the intensity and neurotoxicity of the exposure (Kaukiainen et al., 2004; Keski-Sa¨ntti et al., 2010)), was almost the same 11.0 (5.5–18) vs. 11.4 (6–21) OELY. The occupations and work tasks were the same in both groups, since the SPC screening was directed

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Referred cases, n Diagnosed cases, n Age, years, mean (min–max) Sex, n (m/f) Exposure in years, mean (min–max) Exposure in OELY, mean (min–max) Retirement rate at time of diagnosis, % Retirement rate at one-year follow-up

SPC screeninga

OHS screeningb

32 15 (47%) 57.5 (44.7–62.6)

128 19 (14.8%) 56.8 (51.7–60.1)

14/1 38.9 (19–47)

19/0 34.0 (10–42)

11.0 (5.5–18)

11.4 (6–21)

6.7

74

3

All the costs were computed using an average hourly cost for nurses (103 USD) and physicians (206 USD), and all the calculations were converted to the 2013 price level and the exchange rate between the USD and the Euro on October 26th 2013.

p

2.3. Workability of CSE patients

0.0004

95

a

Furu et al. (2012). Keski-Sa¨ntti et al. (2010). SPC screening, stepwise postal-clinical screening, in which solvent-exposed workers were screened with postal query followed by clinical examinations. OHS screening, existing health check based screening practice of occupational health services. OELY, occupational exposure limit year, index of life-time exposure taking into account the intensity and neurotoxicity of the exposure. b

at the fields that the previous study revealed as harboring the most CSE cases (Keski-Sa¨ntti et al., 2010) (Table 1). 2.2. Economic evaluation This study calculated the costs of the stepwise screening using a postal survey followed by clinical examinations (Furu et al., 2012). The next step was to add the price of the screening procedure to the price of the differential diagnostic examinations at FIOH, and to divide this sum by the number of new verified CSE cases, rendering the cost of detecting one new CSE case with occupational disease by screening. The value of one month’s work was calculated on the basis of the average monthly income of building, maintenance and manufacturing work. The economic value of the loss of production due to early retirement was calculated by adding employer costs to average annual salary. The total annual average salary cost was determined by multiplying the monthly wage by 12.5 (0.5 month mandatory additional vacation salary in Finland) and adding employers’ wage-related additional costs, which were 26% of paid salary in 2010 (www.ek.fi). The value of one month’s work is derived by dividing this value by twelve, and the value of one days’ work by dividing the one month value by 22, the number of working days per month. In order for the screening to be cost effective, the working career of a single employee should be extended at least until the cost of detecting one CSE case is covered. This can be calculated by dividing the cost of detecting one new CSE case with the average value of one month’s work. In the cost analysis of the existing OHS screening (Keski-Sa¨ntti et al., 2010), we assumed that respective OHS units had followed official national CSE screening recommendations (Sainio et al., 2006). Thus, it was possible to approximate the costs of this routine, in which 128 CSE suspected cases were detected at OHS and referred to FIOH, and finally 19 new cases were diagnosed. We approximated that organizing and performing health checks takes one hour of nurse’s work time and half an hour of physician’s work time. Neither group included the costs for preliminary differential diagnostics before referral to FIOH i.e. ruling out common differential diagnostic conditions, since it was not possible to estimate how many of the OHS screened patients would have been in need of these examinations.

In this study we compared the retirement rate, i.e. the proportion of patients that end up on disability pension due to CSE, of CSE cases in the SPC screening group with that of cases detected between 2002 and 2004 by existing OHS screening. The retirement status of the CSE cases detected by the SPC screening and OHS screening were known at the time of diagnosis. The retirement status of the OHS screened cases is also known at the one year control (Keski-Sa¨ntti et al., 2010). In comparisons, the retirement rates at the time of diagnosis were used. The Work Ability Index (WAI) is a validated tool for assessing work ability, the subjective evaluation of a worker’s health and resources, and the demands of work. It is widely used in both clinical settings and in research (de Zwart et al., 2002; Radkiewicz and Winderszal-Bazyl, 2005; Torge´n, 2005; Lin et al., 2006; Ilmarinen, 2007; Martus et al., 2010; Coomer and Houdmont, 2013). WAI scores are classified as follows: 44–49 excellent, 37–43 good, 28–36 moderate and 7–27 poor. Poor to moderate WAI scores predict early disability pensions and long sick leaves (Liira et al., 2000; Alavinia et al., 2009; Sell, 2009), mortality and disability (von Bonsdorff et al., 2011), and appear to be associated with lower productivity and quality of work (Tuomi et al., 2001). The WAI has not been previously used to estimate CSE patients’ work ability, and thus, the WAI scores of the SPC screened CSE cases were compared with comprehensive Finnish reference material representing building, maintenance and manufacturing workers in general, since they represent the same gender, age group, nationality and social class (Gould et al., 2006). Only men were included in this comparison since there was only one female in the SPC group.

3. Results 3.1. Cost of detecting one new CSE case The cost of the CSE screening process, in which 3640 workers were screened by postal survey followed by a clinical first-stage evaluation of 83 symptomatic and solvent-exposed cases, was 62,795 USD in total, of which 9545 USD consisted of the loss of working time of the screened workers. These 32 cases of suspected CSE were referred to FIOH’s outpatient clinic for further examinations for an occupational disease, which cost 185,481 USD in total. Adding this to the expenses of the previous levels of screening results in a sum of 248,481 USD. Dividing this with the amount of verified CSE cases (n = 15), gives a total cost of 16,552 USD/new verified CSE case. The approximated expenses for the national recommended routine, in which OHS screens 20,000 solvent-exposed workers, are 6,933,184 USD, of which 2,300,000 USD consisted of loss of working time. In addition, the diagnostic examinations at FIOH’s outpatient clinic of 128 workers with suspected CSE cost 623,280 USD. In total this makes 7,556,465 USD. Dividing this with the amount of new verified CSE cases (n = 19), gives a total cost of 397,709 USD/new CSE case detected (Table 2). 3.2. Career extension needed to cover the cost of screening The average income of building, maintenance and manufacturing work is 3857 USD (Official Statistics of Finland, 2013). Thus the

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Table 2 Costs of detecting one new chronic solvent encephalopathy case by stepwise postal-clinical screening and by the existing screening practice of occupational health services. SPC screeninga n Detecting suspected CSE cases Postal questionnaire Response handling Processing by hand Clinical examinations Loss of working time ½ day/person Laboratory Referrals Total screening price

OHS screeningb USD

3640 1740 129 83 83

7722 6260 1776 34,196 9545

32 62,795

3296

n

USD

20,000 20,000 20,000 128 6,933,184

4,120,000 2,300,000 500,000 13,184

Diagnostic examinationsc Diagnostic examinations Loss of working time 2 days/person Differential diagnostic follow-up Loss of working time 1 day/person Total price of diagnosis

32 32 20 20

134,977 7360 40,844 2300 185,481

128 128 25 25

Screening and diagnostic examinations Total price (screening + diagnostics) Price of detecting one CSE case

15

248,276 16,552

19

539,911 29,440 51,055 2875 623,281

7,556,465 397,709

Work career extension needeed to cover costs 3.27 months

78.57 months =6.5 years

SPC screening, stepwise postal-clinical screening, in which solvent-exposed workers were screened with postal query followed by clinical examinations. OHS screening, existing health check based screening practice of occupational health services. CSE, chronic solvent encephalopathy. a Furu et al. (2012). b Keski-Sa¨ntti et al. (2010). c Diagnostic examinations of cases with suspected occupational CSE were carried out at the Finnish Institute of Occupational Health.

value of one month’s work equals 5062 USD per month, and the value of one day’s work 230 USD, correspondingly. Detecting one new CSE case using postal screening combined with clinical examinations costs 16,552 USD. Dividing 16,552 USD with 5062 USD/month results in 3.27 months. Thus, extending the workers’ careers by at least 3.27 months covers the costs of the SPC screening. Meanwhile, detecting one new CSE with the existing OHS practice equals 397,709 USD. When this is divided by the value of one month’s work, it results in 78.57 months, i.e. 6.5 years altogether (Table 2). 3.3. Work ability of the CSE cases Surprisingly, at the time of diagnosis, only one out of 15 (6.7%) CSE cases detected by the SPC screening ended up on disability pension due to CSE, whereas the work ability of all the others was preserved. Thus, the retirement rate was very low in comparison

with the group of CSE cases detected by the existing OHS routine between 2002 and 2004, in which the retirement rate at the time of diagnosis was 74%, (p = 0.0004) and finally 95% at one-year followup (disability pension in 18 out of 19 cases) (Keski-Sa¨ntti et al., 2010). The SPC screened CSE cases had lower total WAI scores than the general population. In the 45 to 54-year age group, and the at least 55-year age group, the mean total WAI of the screened CSE cases was 32.75 and 31.04, respectively, whereas that of the age- and sex-matched general (male) population was 38.08 and 36.71, respectively. However, the difference is significant only in the older age group (p = 0.0390). The proportion of poor and moderate WAI scores (under 37 points out of 49) among the screened CSE cases compared with the general population were 100% and 31.9%, in the 45 to 54-year age group, respectively, and 83.3% and 38.2% in the at least 55-year age group, respectively. Again, the difference is significant only in the older age group (p = 0.0187) (Table 3).

Table 3 Work ability index of male chronic solvent encephalopathy patients detected by stepwise postal-clinical screening compared with workers in the building, maintenance and manufacturing field. WAI scores (mean)

45–54-year-olds At least 55-year-olds

Male CSE patients detected by SPC screeninga

Male building, maintenance and manufacturing workersb

n

Mean (min–max)

SD

n

Mean (min–max)

SD

2 12

32.8 (31–35) 31.0 (16–39)

3.2 7.8

144 34

38.1 (23–46) 36.7 (14–49)

5.0 8.0

p

0.1319 0.0390

Proportion of poor to moderate WAI scores

45–54-year-olds At least 55-year-olds

n

%

n

%

2 10

100% 83.3%

46 13

31.9% 38.2%

0.2010 0.0187

a

Furu et al. (2012). Gould et al. (2006). WAI, work ability index; CSE, chronic solvent encephalopathy. SPC screening, stepwise postal-clinical screening, in which solvent-exposed workers were screened with postal query followed by clinical examinations. SD, standard deviation. b

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4. Discussion Globally, solvent-exposed workers are not screened for CSE, and only occasional CSE cases are detected in primary health care. In some countries, for example Nordic countries and the Netherlands, occupational health services or other bodies monitor solventexposed workers through regular health checks. This kind of proactive approach has proven to be an effective way of reaching and detecting symptomatic workers with occupational CSE (Kaukiainen et al., 2009a; Furu et al., 2012; Spee et al., 2012). To the best of our knowledge, this is the first time that a detailed economic evaluation has been carried out concerning CSE or other occupational disease screening. As the financial resources of health care are limited, cost and cost effectiveness are crucial factors that are taken into account when deciding whether or not to carry out a screening. We showed that it is possible to screen a relatively rare occupational disease at a reasonable cost. The plausible elements that contributed to cost effective screening are the following. Firstly, the screening was directed at occupational fields that have been recognized as harboring the most CSE cases in Finland (Keski-Sa¨ntti et al., 2010). Workers were contacted using the cheapest method, i.e. a postal survey, which also saves workers’ working time compared to health checks. With well-validated surveys it was possible to reduce the amount of respondents effectively, minimizing false positives (Furu et al., 2012). This considerably reduced the number of individuals who needed the most expensive examinations at the specialist clinic. This was done by ruling out cases with too few symptoms in the Euroquest neurotoxic symptom questionnaire, inadequate solvent exposure, heavy drinking, major depression or other differential diagnostic explanations for the symptoms (Dick, 2006; van der Hoek et al., 2000). The next step, the first stage clinical examination, used only methods feasible and affordable in primary health care and OHS. Workers were actively chosen from trade union and municipal occupational health care unit registers in the area. Thus, the sample was representative, covering 18% of the abundantly solvent-exposed Finnish workers, which was possible due to the high degree of unionization (over 75% of the whole workforce (www.mol.fi)), and OHS coverage (almost 90% (Manninen, 2009)), in Finland. The study was also carried out systematically for a selected population in two regions of Finland and can thus be replicated at even lower costs in professions at CSE risk in other regions of the country. The costs could be further diminished by making the screening web-based. A recent study suggested a proactive screening procedure to detect CSE patients at an earlier stage of the disease (Spee et al., 2012). In our material, only 6.7% (one CSE patient out of 15) ended up on disability pension due to CSE at the time of diagnosis, whereas previous Finnish material shows the retirement rate as 74% at the same time point. The better preserved work ability of screened CSE cases supports the earlier assumption. Moreover, the retirement rate in this group of screened CSE cases was remarkably lower than that of previous CSE studies (Gregersen et al., 1987; Mikkelsen, 1997; van Valen et al., 2009), which supports the utility of postal CSE screening even further. Five suspected CSE cases are still pending in differential diagnostic investigations. However, we know their occupational status: four at work, and one on long sick leave due to another medical condition. If additional verified CSE cases arise, the retirement rate due to CSE will not increase, thus the results would only change in an even more cost effective direction. Even though the screened CSE cases had a low retirement rate, the at least 55-year-old male CSE cases had lower work ability according to the WAI than male building, maintenance and manufacturing workers in general. Since workers with heavy alcohol consumption, severe depression or other major health

5

problems were ruled out already in the postal screening (Furu et al., 2012), CSE may play a major role in the decline of WAI. These cases form a group of workers whose work ability needs extra attention. Firstly, the cessation of solvent exposure is crucial in order to stop progression of the disease. For this we need cooperation between the specialist clinic, OHS or primary health care and the workplace, since this might entail not only better personal protective equipment, but also changes in working arrangements or changing to a new non-exposure work task. Secondly, all possible ways to support the workers’ health should be exploited, and all the other diseases affecting work ability, especially cognitive risk factors, should be under control. Thirdly, alterations in job descriptions or working times may be needed at the workplace if cognitive capacity is affected. Vocational support may also be needed. This study only took the direct costs of early retirement into account. However, the indirect costs of CSE might be considerable. Work ability and productiveness might be diminished already years before diagnosis. In addition, early retirement leads to diminished tax income and lower pension levels. There are methods to estimate these indirect costs of disease (Koopmanschap et al., 1995), but they were beyond the scope of this study. In the case of an aging worker with CSE, the cognitive changes caused by CSE may be worsened by the effects of normal aging (Nilson et al., 2002). This might mean a greater need for support services for the elderly. Taking all these costs of delayed diagnosis with higher disability and early retirement into consideration, the more effective screening by postal query followed by clinical examinations may be even more beneficial. In both screening methods, SPC and OHS screening, the preliminary differential diagnostic examinations were done before referral. In this study, 48% (15 out of 32) of suspected CSE cases detected by the screening procedure and sent to FIOH for examination for an occupational disease were finally diagnosed with verified CSE as an occupational disease, whereas among the OHS screened group the corresponding amount was 14.8%. This suggests that SPC screening directed at the highest risk groups is more effective than the normal OHS procedure. It also suggests that SPC screening carries out preliminary differential diagnostics, for example ruling out depression and heavy drinking, more effectively and detects CSE cases with fewer other general medical problems than OHS screening, and is in accordance with a recent Dutch study (Spee et al., 2012). However, the differential diagnostics of milder CSE cases detected by SPC screening were also affected by milder non-occupational causes affecting cognition. The screened CSE cases were somewhat older that those of the reference group and had worked longer in solvent-exposed tasks. However, their life-time cumulative solvent exposure by OELY was almost the same. This might speak for the declined exposure levels, since a longer time period is needed to gather the same exposure, and is in accordance with previous suggestions (Keski-Sa¨ntti et al., 2010). The CSE cases in both groups had all gone through the same thorough diagnostic process and thus the same diagnostic criteria were used. This is due to current Finnish practice in which all suspected CSE cases are examined at FIOH’s outpatient clinic. One limitation of this study is that the economic evaluation of the OHS screening is based on an approximation of the recommended screening practice. Another limitation of this study is that the number of screened and diagnosed CSE cases both in this study and in the reference group is limited; 15 and 19 respectively. Screening a relatively rare occupational disease in a rather small country (Finland’s workforce is 2.5 million) is unlikely to yield larger numbers. However, since the difference in retirement rate is considerable, it is not likely to be affected by group size. Since, the

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size of both screening populations is different (3640 vs. 20,000), we chose to use an economic evaluation method in which the final result, the cost of one detected case, is not affected by the number of screened workers. The costs of detecting one new CSE case were over 20 times higher with OHS screening than SPC screening. However, even the more inexpensive method does not necessarily cover its costs if the detection of a new case does not lead to work career extension long enough. One limitation of this study is that we cannot be sure that this group of 15 CSE cases would have retired prematurely, nor did we find a group of workers that represents milder cases that would never have been detected otherwise and who would have continued until normal retirement age. However, in the SPC screening group, a quite short time period, an additional three to four months of work life would cover the costs of screening. As millions of workers are exposed to solvents, and up to 20% of them experience the inconvenience of exposure (Tuomi and Ahonen, 2010), the importance of cost effective screening is even greater. In addition to nervous system effects, solvents may also contribute to ill health by multisystem health effects (Xiao and Levin, 2000). Thus, exposure to solvents must be considered a risk factor to the work-related fraction of public health problems. The design of the current study does not allow the estimation of the burden and costs of these effects, but successful early-phase screening of adverse effects would have benefits even here. This screening project was carried out in a highly industrialized country in which solvent exposure levels have declined in recent decades. Nevertheless, the screening succeeded in detecting new CSE cases, and did so cost effectively. If a similar screening project were carried out in a developing country with presumably higher CSE prevalence, the price of detecting one case would be even lower, and screening would be even more cost effective. The screening was carried out with the high cost levels of a developed country. However, it is probable that the proportional result would not be very different elsewhere, since costs and wage levels correspond. The first steps of the screening were carried out with relatively low cost methods that are applicable to primary health care, which makes the screening method globally feasible. It is also possible that this kind of directed and proactive approach would be beneficial for detecting other occupational diseases. 5. Conclusions Stepwise CSE screening with postal query followed by clinical examinations detects new CSE cases at significantly lower costs than health check based national routines. Detecting CSE cases at an earlier stage of the disease may prevent early retirement. Conflict of interest statement None. Funding sources This study was financed by Finnish Institute of Occupational Health (FIOH) and partly by Finnish Ministry of Social Affairs and Health.

Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.neuro.2013. 12.013.

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