a Te Röpü Rangahau Hauora a Eru Pömare (Eru Pömare Mäori Health Research Centre), Wellington School of Medicine and Health Sciences, University of Otago, Wellington, New Zealand.
b Department of Public Health, Wellington School of Medicine and Health Sciences, Wellington, New Zealand.
c Te Röpü Rangahau Hauora o Ngäi Tahu, University of Otago, Wellington, New Zealand.
d Ngäti Kahungunu Iwi Incorporated, 509 Orchard Road, Hastings, New Zealand.
Correspondence: Vera Keefe, Te Röpü Rangahau Hauora a Eru Pömare, Wellington School of Medicine and Health Sciences, Box 7343, Wellington South, Aotearoa/New Zealand. E-mail: tmhvko{at}wnmeds.ac.nz
Abstract
Background The association between unemployment and poor health outcomes is well documented. Significant debate exists as to whether unemployment causes ill health or whether those with poor health find it harder to obtain and maintain employment. Factory closure studies are well placed to comment on causation. The objective of this study was to investigate associations between involuntary job loss, mortality and serious illness.
Methods An 8-year follow-up of workers from two meat-processing plants in the Hawkes Bay region of New Zealand. A cohort (n = 1945) made redundant in 1986 was compared with a cohort (n = 1767) from the neighbouring plant that remained open until 1994. Incidence rates for mortality, cancer registrations and admissions to public hospitals were derived from record linkage with routinely collected national data.
Results Follow-up for the period 19861994 was 96% complete for both plants. Among the cohort made redundant in 1986, there was an increased risk of serious self-harm which led to hospitalization or death (adjusted for age, sex and ethnicity relative risk [RR] = 2.47; 95% CI: 1.045.89) compared to the employed cohort. The RR of admission to hospital with a mental health diagnosis was 1.17 (95% CI: 0.682.01). There were no other statistically significant findings.
Conclusions This study has most of the features of an ideal factory closure study, in that it achieved near-complete follow-up of a large workforce made redundant and a similar employed workforce for 8 years. We found that exposure to involuntary job loss increased the risk of mental distress leading to serious self-harm. No other association was found.
Keywords Redundancy, unemployment, self-harm, factory closure, longitudinal studies
Accepted 3 April 2002
There is a well-documented association between unemployment and poorer health outcomes which has largely been described through the experiences of western nations during periods of economic restructuring in the latter decades of the 20th century.113 Despite a large number of studies, there is still significant debate around the relative influences of selection and/or causation in the explanation of this relationship.7,12,13
Important in the causal-selection debate are factory closure studies, where job-loss affects the entire factory staff, and becoming unemployed is not dependent on selection factors such as lifestyle, health status, or the personal and socioeconomic characteristics of individuals.13 Factory closure studies to date have been hampered by several weaknesses: notably small study populations, lack of an appropriate control group, and a short duration of follow-up. However, evidence of short-term adverse effects on mental well-being has been published.4,14,15 Other studies have demonstrated increased use of primary care service5 and hospitalization for certain conditions.8 While one factory closure study described an excess of suicide,2 in general factory closure studies have not had the power to demonstrate significant changes in rare outcomes such as death.
In the mid-1980s, New Zealand elected a reformist Labour government that adopted strongly pro-market economic policies. While unemployment was increasing prior to this time, it was the fundamental shift in the economic and social policy after 1985 that produced a significant contraction in employment in New Zealand.16 Between December 1986 and December 1994 the unemployment rate in New Zealand increased from 3.6% to 6.8%.17 New Zealand was differentially affected by this change from a job-rich to job-poor society. Most affected were blue-collar workers, Mäori (indigenous New Zealanders), and provincial New Zealanders. Furthermore, a number of sectors became vulnerable to downsizing, especially the state sector and industries where government subsidies were removed. The meat-processing industry was one of these.
This study draws on two meat-processing plants in provincial New Zealand and their experience in the rationalization of the meat industry during economic restructuring. The Hawkes Bay Farmers Meat Co-operative (Whakatu) was established in 1912. It was the largest meat processing plant in the Southern Hemisphere and was considered an industry flagship.18 When Whakatu closed unexpectedly in October 1986, 2160 people lost their jobs, most of them meat workers, rocking the region and touching national consciousness.
The Tomoana plant was founded in the late l9th century and a 100 years later was one of New Zealands largest meat processing plants, located a few kilometres from Whakatu in the same regional environment, with workers attending the same health services. Tomoana remained open until 19 August 1994, when Weddel NZ went into receivership and overnight Tomoana and four other New Zealand meat-processing plants were forced to close.
This study sought to investigate the health impact of involuntary job loss among meat-processing workers in regional New Zealand by reviewing subsequent hospital admissions, cancer registrations and mortality.
Methods
This retrospective cohort study was designed in two parts. An initial pre-closure study in order to test the suitability of the control cohort (Tomoana), was followed by a post-closure study, to compare the health of those from the closed meat processing plant (Whakatu) with the health of those in the control plant.
The study began with consultation with local communities including the regional Mäori tribal authority and Meat Workers and Related Trades Union. Community processes to support the study and report results were established.19 Ethical approval was obtained from the regional ethics committee.
Information on employees was obtained through personnel records, obtained for both meat plants. For Whakatu (redundancy group), records covered 1 January 1977 to 10 October 1986, and for Tomoana (control group) from 1 January 1977 to 19 August 1994. Information extracted included: full name, sex, date of birth, last known address, first and last dates of employment, and last department worked in.
Health information on employees was obtained by linking personnel records with computerized national health datasets from the New Zealand Health Information Service, using name and date of birth, aided by addresses. Matching of names using phonetic and mis-spelling routines,20 and allowing for minor differences in dates of birth, was followed by visual matching. National death records were available from 1977, admissions to psychiatric institutions or units (mental health admissions) from 1982, and all hospital admissions from 1988. Hospital admissions for 19861987 were incomplete during the period of transition to new national patient identifiers. Workers were classified as Mäori if they had indicated Mäori descent on the electoral roll, if they had been coded as Mäori on national health databases or if the research team had personal knowledge of their ethnicity.
Inclusion and exclusion criteria
Inclusion criteria for the pre-closure study included all those who had worked at any time between 1 January 1977 and 10 October 1986 in either Tomoana or Whakatu.
Inclusion criteria for the post-closure study included all meat workers at Whakatu and Tomoana who worked on the shop floor any time between 1 January 1986 and 10 October 1986. Due to the seasonal nature of the meat-processing industry, those expecting to be employed later in the season would have also been affected by the closure. Hence, in addition to current workers at the time of closure, an extended time period from 1 January to 10 October 1986 was used. Those who had worked at both works during that period were assigned to the works of their last employment (eight workers shifted from Whakatu to Tomoana and one from Tomoana to Whakatu).
Exclusion criteria included any workers starting at Tomoana after 10 October 1986. Also, office staff were excluded, as Whakatu records did not include those of clerical staff. Halal butchers (n = 95) were excluded as they were employed by the Department of Foreign Affairs and some returned to their country of origin following the closure and were therefore unavailable for follow-up. A total of 24 Halal butchers (8 from Whakatu and 16 from Tomoana) were in the post-closure cohorts. Those with no date of birth information were excluded (n = 160, 58 from Whakatu and 102 from Tomoana) as their death and/or hospital admission was unlikely to be ascertainable. Of these, 41 were in the post-closure cohorts (13 from Whakatu and 28 from Tomoana). Ninety-nine people opted out of the study. There were equal numbers of those opting out of the post-closure redundant (n = 19) and comparison (n = 19) cohorts.
Study groups
The pre-closure study included those who had worked at any time during the 10 years between 1 January 1977 and 10 October 1986. This study compared cohorts of 4349 workers from Whakatu and 4080 from the control works, Tomoana. Another 410 had been employed at both works and were excluded from the analysis.
The post-closure cohorts included meat workers employed any time during the 10 months between January 1986 and 10 October 1986. These included 1945 workers made redundant from Whakatu and 1767 workers from the control plant, Tomoana.
Data analysis
Post-closure mortality and hospital admissions (all-cause, and primary cause of: self-inflicted injury, other external injuries, heart disease, stroke, cancer, respiratory disease, and mental health admissions) were compared between the workforces from 10 October 1986 to 19 August 1994 with Coxs regression adjusted for age, sex and ethnicity. Using the PHREG procedure of SAS 8.00, relative risk (RR) estimates and 95% CI were calculated.21
As ethnicity was unknown for 3%, adjustment for ethnicity was made using multiple imputations based on sex, meat works, age and year of hire.22 Person-years were censored at the last date the person was known to be alive and living in New Zealand, as it was assumed that these people then became unavailable for the identification of health outcomes in national mortality and hospital admission databases.
The pre-closure study used the same procedure, where workforces were followed from the workers date of hire or 1 January 1977 whichever was the latest, and were included until 10 October 1986 when follow-up of the pre-closure study ceased. If workers were lost to follow-up during this period, they were censored out of the study as noted above.
As the national dataset did not have full coverage of all hospital admissions until 1988, 2 years after the closure of the Whakatu plant, sensitivity analyses were conducted to determine whether removing admissions for 1986 and 1987 affected the findings.
Tests for departure from the proportional hazard assumption were made using the correlation between the scaled Schoenfeld residuals and time.23 Where there were significant departures from the proportional hazards assumption the plots of the scaled Schoenfeld residuals versus time were examined and the model modified with time dependent covariates.
Results
Table 1 shows the similarity of the socio-demographic characteristics of the two workforces in both the pre-closure and post-closure studies.
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Deaths from other external injuries among the study group were nearly double (RR = 1.90; 95% CI: 0.665.47), motor vehicle crashes being the main contributor. Of these 12 road crash deaths, 7 were drivers (Whakatu n = 4, Tomoana n = 3) and 5 were passenger deaths (Whakatu n = 5, Tomoana n = 0). These and other major causes of death were not significantly different. The RR of death from other selected causes is shown in Table 3.
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Cancer registrations were similar between the two groups during the 8 years post-closure, with 50 registrations among Whakatu and 41 among Tomoana workers giving an RR of 1.17 adjusted for age, sex, ethnicity (95% CI: 0.771.77, P = 0.46).
Table 5 presents findings on self-inflicted injury, both fatal and non-fatal that led to hospital admission. Nineteen of the redundant cohort and seven workers from the comparison cohort had a serious self-harm event. The unadjusted RR of 2.49 (95% CI: 1.055.93) remained significant when adjusted for age, sex and ethnicity (RR = 2.47; 95% CI: 1.045.89).
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Departures from the proportional hazards assumption for redundancy were only statistically significant for all-cause hospitalizations (RR decreased from 1.14 at closure to 0.75 at the end of the study period; P = 0.016), deaths from cancer (RR = 8.600.35; P = 0.018) and hospitalizations for cancer (RR = 2.040.53; P = 0.037).
Discussion
This study assessed the health impact of involuntary job loss following the unexpected closure of a large meat processing plant by comparing the subsequent morbidity and mortality of the workers with that of workers in a nearby plant that did not close. We found that exposure to involuntary job loss more than doubled the risk of serious self-harm over the following 8 years. This association remained after adjustment for possible confounders. The redundant cohort comprised more members who had previously been admitted to a mental health facility. The effect of controlling for this factor was small, although the risk was no longer statistically significant at the 5% level. No association was found for death or hospitalization for other causes.
This study captured only medically serious self-harm that resulted in death or hospitalization for at least 24 hours. Beautrais notes that suicides and serious suicide attempts form two overlapping populations that are far more alike than different.24 By combining self-harm events that had both fatal and serious non-fatal outcomes, we focussed on their commonality as indicators of severe mental distress.
The association between involuntary job loss and mental distress has been described previously.24,14,15 In particular Cobb and Kasl, in the Michigan factory closure study, note an excess of suicide.2 Furthermore, Montgomery et al.25 found unemployment, especially recent unemployment, to be a risk factor for deterioration in mental health, even among those without evidence of previous psychological vulnerability.
Job loss is a stressful life event, often described as a form of bereavement.26 This is consistent with a causal relationship between job loss and ill health. Factory closure studies are well placed to comment on causation.13 Morris and Cook27 described an ideal factory closure study as having the following characteristics: (1) a large number of employees; (2) a similar number of controls in a similar factory; (3) high response rates; (4) data before the closure; (5) both self-reported and objective measures of health; (6) follow-up for 5 (ideally 10) years, and; (7) minimal loss to follow-up. This study has most of these features although measures of self-reported health and total health service use, in particular primary health care, were unavailable.
Factory closure studies can be vulnerable to a health selection bias, where more qualified and more adaptive employees leave after hearing rumours of the impending closure. This would make the workforce at time of closure unrepresentative.28 While there was industry-wide concern among meat workers about proposed plans to substantially reduce the capacity of meat processing plants in the region, Whakatu workers felt secure in their plants reputation and track record. In the 10 months prior to closure, less than 0.5% of the workforce moved from Whakatu to Tomoana. Shareholding companies decided to close one large meat processing plant rather than downsize or close several smaller plants. There is no evidence that the Whakatu closure was related to poor productivity. Industry sources document the closure as a business decision related to rationalization following industry deregulation.18
We found no increased risk of admission for mental health diagnoses among workers in the redundant cohort, despite the increased serious self-harm events. Fagin notes that most mental health symptoms following job-loss are likely to be dealt with by the family doctor except for cases of self-harm.29 But Montgomery et al. noted that those without educational qualifications, who are at greatest risk of becoming unemployed, may also be less likely to seek medical assistance for some mental illnesses.25 However, previous factory closure studies in Britain have shown that redundancy leads to increased use of primary care services and an increase in referrals to secondary services.5 The association of unemployment with increased use of health care is likely to depend, however, on these services being universally available and free of charge at point of use, as in Britain.30 In New Zealand there is usually a cost to the patient when accessing primary health care. Indeed this is the most commonly reported reason for delaying or deferring visits to family doctors.31
Our initial expectation of the study was that there would be an increase in hospital admissions for other diseases and perhaps even mortality among those exposed to redundancy. However, apart from serious self-harm, there was little difference in the RR of hospitalization. Reviewing these findings, we identify three possible explanations.
Firstly, that there was no effect to find. Given the number of endpoints considered, it is possible that the main result is a chance finding. However, the association with serious self-harm is supported by the vast majority of the unemployment literature.3,12
Secondly, the study may not have sufficient power or a study period long enough to detect differences in heart, respiratory, cardiovascular disease or cancer. As both the study and the control group had a younger average age than our initial estimation there were fewer health events than we expected. We were not able to utilize intermediate measures such as primary health care utilization or blood pressure or cholesterol recordings that may have provided more short-term indicators of health impact.
Our third consideration was that the health impact associated with involuntary job loss may be similar to the health impact of continuing to work in an industry facing ongoing rationalization at a time of peak unemployment in New Zealand. Iversens study of a Danish shipyard closure drew attention to the fact that the resultant hospitalization pattern reflects a mixture of changes to occupational hazard as well as the possible impacts of redundancy.8,29
While factory closure studies can illuminate causal influences in the association between unemployment and ill-health, some authors propose that the selection-causation debate is overly simplistic.7 Most now accept that both causal effects and certain selection processes contribute to this association.13 Bartley also notes that unemployment and job insecurity are part of the process whereby health disadvantage is accumulated throughout ones life.12 In this way, unemployment may have long-term and intergenerational effects well beyond the experience of a period of time without work.
The policies that determined New Zealands economic direction in the previous two decades, and our policies on the funding of health services, especially primary care, both singly and in combination, may therefore contribute to increasing health inequalities in New Zealand into the future.
KEY MESSAGES
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Acknowledgments
The authors acknowledge the contribution and support of former freezing workers and their families, former management of Whakatu and Tomoana works, Ngä Taiwhenua o Ngäti Kahungunu, Te Puni Kökiri Hastings, Hastings District Council, Tomoana Resource Centre, Meat and Related Trades Workers Union. We thank all those who have reviewed drafts of this paper for your helpful comments. The Health Research Council of New Zealand funded this study.
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