Underreporting of fatal occupational injuries in ...

Occupational Medicine 2004;54:110–114 DOI: 10.1093/occmed/kqg132

Underreporting of fatal occupational injuries in Catalonia (Spain) Fernando G. Benavides1, Gloria Pérez2, Jordi Martínez3, José Miguel Martínez1, Rosa Gispert2 and Joan Benach1

Background Thoroughness in a given health information system is one of its most important quality indicators. In Spain, in ~30% of serious occupational injuries, there is no information on the final outcome. To assess underreporting of fatal occupational injuries in Catalonia.

Methods

All serious occupational injuries (excluding commuting injuries) reported in Catalonia (Spain) between 1994 and 1998 (n = 7330) were linked with data from the Catalonian Mortality Register, 117 deaths being identified during the year following the injury date. In order to assess whether death could or could not have been related to the prior occupational injury, two experts examined these cases independently.

Results

The experts concluded (κ = 0.98) that 69 (59%) of these deaths were probably related to occupational injuries; the vast majority (n = 65) occurred within 3 months of the injury. This represents an accumulated risk of dying of ~1% for the total of serious injuries, not varying with economic activity or job category. However, this risk varied depending on the form of accident, and the site and nature of the injury.

Conclusions Occupational injury cases, especially serious ones, should be followed up over at least 3 months. These results suggest the importance of carrying out active case-finding and of incorporating the death certificate as one of the documents to be systematically reviewed in order to complete the statistics. Keywords

Fatal work injury; fatality rates; occupational health information system.

Received

16 April 2003

Revised

28 July 2003

Accepted

29 September 2003

annual European statistics on occupational injuries, applying a harmonized methodology [1]. EUROSTAT has published the trend of occupational injuries for 1994–1998, showing that the incidence rate decreased by ~10% for occupational injuries resulting in >3 days absence, and by slightly more than 17% for fatal occupational injuries [2]. Available data until 1998 [3] will be the basis for implementing an appropriate occupational health information system. In order for such systems to fulfil these functions, they must be not only rapid and accessible, but also exhaustive; that is, they must record all cases that occur in a given area and time-span [4]. In Spain, as in other European countries, there is some doubt as to whether the number of deaths attributable to occupational injuries might be higher than that being declared, since ~20% of the total of occupational injury

Introduction Occupational injuries, particularly fatal ones, are unacceptable health events because theoretically they can be avoided. Effective prevention of this problem requires the existence of adequate health information systems capable of identifying the causes and evaluating interventions. Since 1994, the European Union has produced 1 Unitat de Recerca en Salut Laboral, Universitat Pompeu Fabra, Doctor Aiguader, 80, 08003 Barcelona, Spain. 2 Registre de Mortalitat de Catalunya, Servei d’Informació i Estudis, Departament de Sanitat i Seguretat Social, Barcelona, Spain. 3 Centre de Seguretat i Condicions de Salut en el Treball, Departament de Treball, Barcelona, Spain.

Correspondence to: Fernando G. Benavides, Occupational Health Research Unit. Department of Experimental and Health Sciences. Universitat Pompeu Fabra, Doctor Aiguader, 80, 08003 Barcelona, Spain. Tel: +34 9 3542 2525; fax: +34 9 3542 2802; e-mail: [email protected]

Occupational Medicine, Vol. 54 No. 2 © Society of Occupational Medicine 2004; all rights reserved

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Aim

F. G. BENAVIDES ET AL.: FATAL OCCUPATION INJURIES IN CATALONIA 111

cases, in particular serious ones (35%), do not include information regarding outcome [5]. The hypothesis of this study was that some of the people with occupational injuries, especially serious ones, could have died during the year following the date of the injury. The aim of the present study was to assess underreporting of fatal occupational injuries in a sample of serious occupational injuries, during the year following the date of the injury. The study was approved by the Advisory Committee for Treatment of Confidential Information of the Department of Health and Social Security of the Catalonian Government.

Subjects and methods

Results Of the 7330 serious occupational injuries studied, 117 were identified in the CMR as deaths. In the opinion of the experts, 69 (59%) of these 117 deaths were probably related to the occupational injury. Agreement between the experts was excellent (κ = 0.98). In the only discordant case, the corresponding death was finally considered non work-related. If these 69 new deaths probably related to the previous occupational injury found in this study were added to the 776 fatal occupational injuries already registered by the Department of Labour, it would represent an underreporting rate of 8.2% of the total [69/(776 + 69)] fatal occupational injuries in Catalonia. The accumulated risk of dying due to an injury classified as serious, during the year following its occurrence and notification, was estimated to be ~1%. This risk was similar (log rank = 5.65; P = 0.2272) for each of the five years studied, as shown in Figure 1, oscillating between 1.4% in 1994 and 0.6% in 1997. For deaths that were considered to be related to work, the median interval between the injury and the death was 9 days, with a maximum of 117 days. None of the deaths related to serious occupational injuries occurred >4 months after the day of the injury. In addition to the time elapsed since the injury (97% of deaths during the month following the injury were related to the injury), other predictive variables were age (1 year from the date of the injury, since for the purpose of the study only deaths occurring in this period were considered eligible. This criterion is in line with the definition adopted by EUROSTAT of a fatal occupational injury as ‘an injury which causes the death of the victim during the year following the date of the injury’ [1]. The serious occupational injuries for which a death was identified were assessed by two medical experts (one being a specialist in occupational medicine, the other a specialist in primary care) with experience in assessing occupational pathology. Each specialist established independently whether or not the death could have been a consequence of the prior occupational injury. Experts were provided with the details from the injury form and with the death certificate of each one of the cases identified. The accuracy of death certificates is acceptable in Spain [6]. In addition, each specialist had an instruction manual containing judgement criteria. Accordingly, they assessed that the death was probably work-related if (i) there was enough information about the occupational injury and causes of death; and (ii) there was clear evidence supporting a link between occupational injury and causes of death (e.g. death due to head fracture 1 week after date of the occupational injury due to a fall from height). In cases where one of these two criteria was

not fulfilled, they established that the death was not work-related (for example, a cardiovascular disease as the cause of death, with no reference to this disease in the occupational injury certificate, was assessed as not related to work; however, if cardiovascular disease, such as a heart attack, was on the occupational injury certificate and a similar cardiovascular disease was on the death certificate, this death would have been assessed as probably related to work).Where the specialists disagreed, each case was discussed until an agreement was reached. The accumulated risk of dying (up to a maximum of one year after the injury) was estimated by the survival function applying the Kaplan–Meier method [7], with the log-rank test being used to assess statistical significance. Agreement between the experts was measured using the κ index [8]. Distribution of fatal serious occupational injuries according to whether they were work-related or not was compared using Fisher and χ2 tests.

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Figure 1. Distribution of the accumulated risk of dying during the year following a serious occupational injury, for each of the years studied, Catalonia, Spain, 1994–1998.

To our knowledge, this is the first study in assessing the number of unreported deaths probably related to work occurring days after occupational injury. The underreporting rate found in this study was 8.2%. These new 69 deaths that were probably related to the previous occupational injury were not reported in the official statistics. However, any violent or sudden deaths require a medico-legal autopsy and have to be compulsorily declared [9]. This underreporting of fatal occupational injury cases can change the profile of fatal occupational injury statistics, especially in relation to nature of injury, site of injury and form of accident. Logically, these are variables that inform us about injury severity. Moreover, with respect to other characteristics of these 69 newly identified occupational deaths, such as age, sex, economic activity of the firm and job category, we have checked that they do not differ in comparison with declared data (data not shown), implying that underreporting does not result in a selection bias with respect to these variables. However, the 8.2% of fatal occupational injury underreporting could be even higher if injuries classified as minor had also been included in the study, since it is likely that some serious injuries are incorrectly classified as minor. A recent study has shown that the real number of serious occupational injuries was 3.5 times the official number [10]. It is interesting to note that one-third of the deaths attributable to occupational injuries by experts were non-traumatic, mainly ischaemic heart disease and cerebrovascular diseases (17 out of 69). In the case of a cardiovascular disease as the cause of death, without any

Acknowledgements We are grateful to Glòria Ribas for her help with the record linkage program. This work was partly funded by a grant (FIS 00/0864) from the Fondo de Investigaciones Sanitarias.

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Discussion

reference to this disease in the occupational injury form, it was assessed as not related to work. However, if a cardiovascular disease, such as a heart attack, is listed as the cause of occupational injury on the form and a similar cardiovascular disease is on the death certificate, this death was assessed as probably related to work. A similar proportion of non-traumatic occupational injuries are reported in the official statistics (~30%) [5]. This means that the suppression of these deaths in our analysis, just as they are excluded from the European harmonized statistics [1], would reduce the absolute numbers of deaths that were probably work-related, but would not modify the relative magnitude of the underreporting found. These results suggest the need to carry out active case-finding, incorporating the death certificate as one of the documents to be systematically reviewed for the occupational health information system. This approach has already been used in countries such as the USA, where, since 1992, the Bureau of Labour Statistics has had a specifically designed system for generating fatal occupational injury statistics (Census of Fatal Occupational Injuries) [11]. This system includes all fatal occupational injuries confirmed through at least two reliable source documents, such as the death certificate, the application form for injury compensation, and the state and federal agency administrative injury report. Moreover, it has been verified that the death certificate is the document that captures the highest number of cases [12,13]. Implementation of such a procedure would imply adding an ‘injury at work’ item to the death certificate form, which would be marked when applicable. In the USA this item has been shown to have a sensitivity of 78% for detecting true cases of occupational injury deaths [14]. Unfortunately, this approach is not followed in Spain and the rest of the European Union countries. An alternative might consist of systematically recordlinking occupational injury data with death registries, as we have done in this study. However, this solution could be time consuming. Improving our occupational health information system, especially in relation to fatal occupational injuries, must be a priority in order to reduce the burden of occupational injuries. A modification on the death certificate form, introducing an item to complete in the case that death was work-related, should be considered.

F. G. BENAVIDES ET AL.: FATAL OCCUPATION INJURIES IN CATALONIA 113

Table 1. Distribution of fatal serious occupational injuries according to whether they were work-related or not, Catalonia, Spain, 1994–1998 Variable (P value)

Non-work-related

Total

n

(%)

n

(%)

67 2

(58.8) (66.7)

47 1

(41.2) (33.3)

114 3

20 49

(76.9) (53.8)

6 42

(23.1) (46.2)

26 91

59 6 4

(96.7) (75.0) (8.3)

2 2 44

(3.3) (25.0) (91.7)

61 8 48

13 18 17 17 4

(48.1) (56.3) (89.5) (54.8) (50.0)

14 14 2 14 4

(51.9) (43.8) (10.5) (45.2) (50.0)

27 32 19 31 8

16 10 2 21 20

(72.7) (58.8) (10.5) (80.8) (60.6)

6 7 17 5 13

(27.3) (41.2) (89.5) (19.2) (39.4)

22 17 19 26 33

24 9 1 15 16 4

(66.7) (40.9) (16.7) (83.3) (57.1) (57.1)

12 13 5 3 12 3

(33.3) (59.1) (83.3) (16.7) (42.9) (42.9)

36 22 6 18 28 7

1 19 21 28

(20.0) (54.3) (60.0) (66.7)

4 16 14 14

(80.0) (45.7) (40.0) (33.3)

5 35 35 42

2 6 8 36 17 69

(50.0) (60.0) (61.5) (53.7) (73.9) (59.0)

2 4 5 31 6 48

(50.0) (40.0) (38.5) (46.3) (26.1) (41.0)

4 10 13 67 23 117

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Sex (P = 1.000) Male Female Age (P = 0.035) ≤35 years >35 years Follow-up time (P < 0.001) 3 months Nature of injury (P = 0.038) Fractures Shock Multiples injuries Heart attack/other pathologies Others Site of injury (P < 0.001) Head, face and neck Trunk Limbs Multiple injuries Internal organs Form of accident (P = 0.023) Falls Objects Over-exertion Vehicles Non-traumatic Other Economic activity (P = 0.233) Agriculture and fishing Industrial Construction Services Job category (P = 0.538) Managerial and professional Intermediate occupations Clerks Skilled manual occupations Labourers and apprentices Total

Work-related

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11. Available on: www.bls.gov/oshcfoi1.htm (visited on 24 February 2003). 12. Russell J, Conroy C. Representativeness of deaths identified through the injury-at-work item on the death certificate: implications for surveillance. Am J Public Health 1991;81:1613–1618. 13. Stout N, Bell C. Effectiveness of source documents for

identifying fatal occupational injuries: a synthesis of studies. Am J Public Health 1991;81:725–728. 14. Kraus JF, Peek C, Silberman T, Anderson C. The accuracy of death certificates in identifying work-related fatal injuries. Am J Epidemiol 1995;141:973–979.

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