NOHSAC : Methods and Systems Used to Measure and Monitor Occupational Disease and Injury in New Zealand : Tech Report 2

1.2 Occupational Injury

The workplace is a significant contributor to injuries and injury fatalities in New Zealand. However, the systems currently in place for collecting and coding occupational injury surveillance data suffer from a number of limitations that hamper efforts to quantify the nature and extent of occupational injury. Four significant initiatives have explored the feasibility of merging injury data sets from various agencies, each project building upon the learnings from the previous one. In doing so, these studies have reached conclusions about the strengths, weaknesses, and gaps of the various data sources and begun to strengthen New Zealand’s occupational injury surveillance capacity. These are the Work-Related Fatal Injury Study, the Accident Insurance Regulator, the New Zealand Injury Data Review, and the Injury Statistics Project Pilot. The latter is described below and is followed by a summary of the systems covered by this review.

Injury Information Manager

The Injury Information Manager role was established to produce coherent injury statistics in New Zealand, by collecting and aggregating injury-related information. Statistics New Zealand was appointed Injury Information Manager in June 2002. The Injury Information Manager is directly accountable to the Ministers of Statistics and ACC. The Ministers purchase outputs from the Information Manager, but do not control the methodology used to produce the results or the manner of their publication and dissemination. The Ministers also receive advice from a Ministerial Advisory Panel, which provides advice on the data sets, reporting, and the direction and strategy of the injury surveillance model.

Development of the new injury statistics system began in August 2002 and was expected to span three years. In the first year of the project, a trial integration (pilot) stage was carried out using ACC and NMDS data (which represent the bulk of the available injury information). The primary objective of the pilot study was to establish the feasibility of integrating the two primary sources of data. The feasibility report from the pilot study was submitted in May 2004.

The feasibility report concluded that ACC and NZHIS data can be integrated to a suitable level of quality and that confidentialised versions of the NZHIS and ACC unique identifiers are suitable for completing the record linkage process to an acceptable level of accuracy for statistical purposes. The creation of an injury database, based on the pilot prototype, is considered to be feasible.

Occupational diseases have been specifically excluded from the project, at least for the time being. The Injury Data Review recommended that, in principle, occupational disease should be included in the definition of injury. However, it was excluded from the project until a clear picture of the incidence of occupational injuries in New Zealand is obtained, the surveillance systems measuring occupational disease can be improved, and further research can be undertaken to decide the most appropriate means of occupational disease surveillance. As a result, the project has taken deliberate measures to identify and exclude occupational disease cases. This is appropriate since the systems and methods required for surveillance of occupational disease differ from those required for surveillance of occupational injury. It is therefore important that systems and methods appropriate for occupational disease surveillance are developed and strengthened (as identified above), and it is inappropriate to simply “add on” surveillance of occupational disease to the work of the Injury Information Manager.

The next stages of the project will progressively extend the coverage of the injury database to further data sources. Statistics New Zealand plans that, by December 2005, it will have satisfactorily completed basic spreadsheets combining all available data. Providing improved access to the data will then become a priority, including a view to providing access to the data via the internet during 2006.

Once numbers of injuries have successfully been established using all available data sources, other measures will be developed, including determining the number of injured persons and developing time-based risk indicators related to various exposures, occupations, and other factors.

Part of the Injury Information Manager’s role is to identify information gaps and system solutions to create a robust and complete view of injury in New Zealand. Therefore, it is anticipated that the Injury Information Manager may at some point, seek to influence the way data is collected by the source agencies.

Death Certificates and Coroners’ Reports

Most occupational injury deaths, apart from motor vehicle accidents and bystander deaths, would be investigated by the coroner. As noted earlier, coroners’ findings are not recorded electronically, and this represents a major barrier to the efficient retrieval of surveillance information. Medical certificates of causes of death do not include an indicator of work-relatedness.

National Minimum Data set (NMDS)

The NMDS records hospital inpatient and day patient discharges. As noted earlier, the recording of occupation is inadequate for the surveillance of occupational injury, as it is under-recorded and is restricted to free-text information.

Health and Safety Accident Recording Database (HASARD)

HASARD records serious harm notifications received by OSH. Occupational health and safety legislation requires employers to notify OSH about workers who suffer serious harm as a result of their work.

HASARD currently has a low potential to contribute to the surveillance of occupational injury. Key problems include under-reporting of serious harm by employers, a system design that does not lend itself well to the aggregation of data for surveillance purposes, a low state of readiness of the data set for integration with other collections, and work practices that are intended to support efficient investigations and do not always support the recording of high-quality data.

Serious harm notifications to OSH tend to contribute to the prevention of the recurrence of harm through the identification of learnings from individual investigations, rather than aggregated data.

Accident Compensation Corporation (ACC) Claims Database

The ACC claims database provides the most complete available coverage of most types of injury and is the only major source of statistics on “minor” occupational injury, due to its comprehensive coverage of work-related injuries. The financial incentive for individuals to claim also facilitates a high level of capture, but by no means guarantees complete capture of eligible cases. However, there are some gaps in coverage. For example, the scheme excludes incapacity during the first week of a work-related injury (for which the employer must compensate the employee), and fatal accidents (unless a claim is made for funeral expenses or support for dependants).

The structure and coding systems of the ACC database are, in many respects, well suited to the surveillance of occupational injury, including fields which can be used to capture unique identifiers, occupation, work-relatedness, industry, diagnosis, and costs. However, the overriding functions of the ACC database have been administrative and have therefore not always been consistent with surveillance needs. In particular, claims administration and case management do not require complete and accurate data on occupation and require only partial use of the work-relatedness flag (which positively identifies most occupational injuries, apart from motor vehicle accidents). Also, the scheme’s eligibility rules may lead to distortions in the coding of diagnoses.

National Poisons Centre

The National Poisons Centre (NPC) is based within the University of Otago and aims to provide information and advice, 24 hours a day to health professionals, organisations, and the general public about the toxic effects of chemicals. The NPC logs all calls it receives in a database. The database provides the most comprehensive available coverage of poisoning events. However, occupational details are not recorded, and the personal information recorded, such as name and telephone number, are insufficient to enable linkage with other data sets at a micro level.

Environmental Risk Management Authority (ERMA)

ERMA is developing its surveillance capability. Current data analysis is based on aggregated and confidentialised data from a range of sources, including the NMDS, Fire Service, HASARD, and some directly received reports of hazardous substance incidents. A Chemical Injuries Surveillance System is under development.

Civil Aviation Authority (CAA)

The Civil Aviation Authority (CAA) establishes civil aviation safety and security standards and monitors adherence to those standards. The principal function of the CAA is to promote safety at reasonable cost. The CAA carries out accident and incident investigations and collates findings to establish an industry-wide safety picture. From May 2003, the CAA has also been mandated to receive serious harm notifications and undertake occupational safety and health investigations in relation to aircraft as workplaces.

By definition, agencies such as the CAA cover a small percentage of the population of work-related deaths and injuries. Nevertheless, these agencies may identify deaths and injuries which are not recorded by ACC or OSH. CAA data is structured around events (rather than individuals). Limited and broadly-categorised injury details are captured. Pilots’ and crew members’ names are recorded. Identifying details of passengers are not recorded. Serious harm reports are not copied to OSH for inclusion on the HASARD database.

Maritime New Zealand (MNZ)

The principal objective of Maritime New Zealand (MNZ) is to undertake its safety, security, marine protection, and other functions in a way that contributes to the aim of achieving an integrated, safe, responsive, and sustainable transport system. The Accident Investigation Division of MNZ maintains a database to record and analyse common causes of accidents. From May 2003, MNZ has been designated under the HSE Act to receive serious harm notifications and undertake occupational safety and health investigations in relation to ships as places of work. Prior to that time, occupational safety and health for crew on board commercial ships was covered under Part II of the Maritime Transport Act.

As a specialist agency, MNZ covers a small percentage of the population of work-related deaths and injuries, but may be able to identify some deaths and injuries not recorded by ACC or OSH. The database records identifying details of injured people and, where the injured person is a seafarer, details of their occupation. Injury type, site, and seriousness of the injury are categorised at a broad level. Serious harm reports are not copied to OSH for inclusion on the HASARD database.

Land Transport Safety Authority (LTSA)

The Land Transport Safety Authority (LTSA) existed to promote land transport safety at reasonable cost. The LTSA monitored and analysed data relating to road and rail accidents and incidents, and maintained a database of traffic crash reports recorded by police when they attend crashes. The database has been used to manage, analyse, and map traffic crash and related data, which helps to determine road safety funding allocations, targeting of road safety programmes, and monitoring of their performance. The government’s recent Transport Sector Review resulted in the creation of a new Crown entity called Land Transport New Zealand to undertake the activities of Transfund NZ and the LTSA other than policy advice functions, which transferred to the Ministry of Transport. Transfund NZ and LTSA were disestablished. Some, but not all, of the LTSA functions relating to crash monitoring and analysis have transferred to the Ministry.

Crash reports include details of who was involved, where the crash occurred, when and how it happened, the type of vehicles involved, the people who were not in vehicles, information about the crash environment, and a crash diagram. Occupational details are not categorised in routine crash reports. Work-relatedness is not recorded.

The Commercial Vehicle Investigation Unit (CVIU) of the New Zealand Police investigates accidents involving heavy vehicles, and this data is also forwarded to LTSA. Therefore, the occupational group involved in road transport using heavy vehicles is covered. However, other occupational groups in the transport industry (such as couriers) and the many other occupations that involve regular road travel, are not identified.

Forest Research Centre For Human Factors and Ergonomics (COHFE)

The Forest Research Centre for Human Factors and Ergonomics (COHFE) maintains an accident reporting scheme for the forestry industry which contains 20 years’ data on logging injuries, including details of injuries sustained, days of work lost, and near miss events. Reporting is voluntary, but the 16 largest forestry companies participate, together accounting for an estimated 60–80% of the forestry workforce. There is also an exposures database which records total hours of work per month for the reporting companies, providing denominator data for analysis of injury rates. COHFE enjoys strong credibility within the industry, with support from all of the largest employers, and goodwill developed through COHFE fostering networks within the companies, which provide regular feedback on the data. As a result, the data is highly complete and accurate (for the participating companies) and is valued by those who contribute injury information.

Strengths, Weaknesses, and Gaps

The key strengths across the systems are:

the positive progress being made by the Injury Information Manager toward making the best use of the available data and producing a comprehensive database of injuries in New Zealand
the high level of capture of occupational injuries within the ACC claims database (due to comprehensive personal injury cover and financial incentives to claim), some of which are positively identified as being work-related
the existence of two unique identifiers (NHI number and ACC45 claim number) which the Injury Information Manager has shown can effectively facilitate the linkage of the ACC and NMDS data sets and should work with a similar degree of success for the Mortality Collection
the use of ICD-10 as a common coding standard across all three of the most promising data sets (in terms of their coverage)
sufficient coding of industry, occupation, activity, and mechanism data within the ACC database, to facilitate some analysis of risk factors and contributing factors and help identify priority areas for further research
ready access to timely data and advice on its interpretation.

Key weaknesses include:

poor coding of occupation, industry, work-relatedness, and ethnicity in most databases
a lack of capture of occupational history and inability to determine the victim’s current occupation at the time of the injury or death
very little information on the costs of occupational injury in New Zealand (other than ACC data)
the low potential of the HASARD system to contribute significantly to occupational injury surveillance, due to under-reporting and weaknesses in system design.

Gaps have been considered along three dimensions:

Vertical – cases not captured by the systems: Occupational injuries that do not result in an ACC claim will only be captured if they are positively identified as being work-related in the Mortality Collection, reported to OSH and recorded in the HASARD system, or can be identified in the NMDS on the basis of E codes. ACC data provides limited coverage of work-related fatalities and does not reliably record work-relatedness against injuries to commuters, bystanders, or volunteers. Another potential gap is minor injuries that result in no treatment costs and/or less than one week off work.
Horizontal – missing information about cases: The principal gap in data collection is the lack of standardised coding of occupation in the Mortality Collection, NMDS, and, to a lesser extent, in HASARD.
Temporal – coverage and consistency over time: Data should be relatively consistent across the main data sets since 2000. Key changes in the data sets are covered within the review.

Opportunities for Improvement

A range of opportunities for improvement have been identified purely with regard to their desirability from an occupational injury surveillance perspective, and without consideration of legislative, policy, or budgetary implications:

Administration and management

Continue the work of the Injury Information Manager to maintain and enhance New Zealand’s ability to make use of the available injury data, through the production of a comprehensive database of injuries.

Data Collection

Take deliberate steps to increase reporting of suspected cases to HASARD, including research on barriers and enablers to occupational injury reporting, and education/marketing campaigns to address the barriers and enablers.
Improve recording of occupation in NZHIS data, including introducing the standard Statistics New Zealand coding system into the Mortality Collection, NZCR, and NMDS; coding the backlog of occupation using methods recently recommended in another study; including occupation in the NHI database; and opportunistically recording longitudinal occupation information on the NHI database each time a patient presents.
Extend and improve the coding of industry in NZHIS and OSH data, in order to add depth to the information captured in the occupation field by including industry as a variable in the Mortality Collection, NZCR, and NMDS using the standard Statistics New Zealand classification system; and aligning the industry classification system in NODS/HASARD with the Statistics New Zealand system.
Collect additional information on work-relatedness and occupation history, by developing a common definition of work-relatedness for OSH and NZHIS; and developing common definitions and fields for recording current occupation, usual occupation, and occupation history.

Accuracy

Improve the use of the work-related E codes in ICD-10-AM 3rd Edition.
Code work-relatedness and occupation for all ACC claims.
Review the classification and field structures in NODS/HASARD for recording occupation, industry, agent and mechanism, with a view to aligning these with standard classification and coding systems and using hierarchical pick-lists for data entry.
Ensure NODS data is updated upon completion of each investigation.