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Abstract
Background The ‘Prospective Outcomes of Injury Study–10 years on’ (POIS-10) aims to contribute to improving long-term disability, health and well-being outcomes for injured New Zealanders. This brief report describes recruitment, characteristics and key outcomes to 12 years post-injury.
Methods Between 2007 and 2009, the study recruited 2856 people, including 566 Māori, from New Zealand’s Accident Compensation Corporation’s entitlement claims register. People experienced a range of injury types, causes and settings; 25% had been hospitalised for their injury. POIS-10 data were primarily collected via interviewer-administered structured questionnaires.
Results Of the original participants, 2068 (92%) were eligible for follow-up in POIS-10. Of these, 1543 (75%) people participated between March 2020 and July 2021, including 240 Māori. Half of the participants (n=757; 50%) reported ongoing problems attributed to their injury 12 years earlier. Most reported difficulties with items assessing disability (WHO Disability Assessment Schedule II). For health-related quality of life (HRQoL), measured using the EQ-5D-5L, the prevalence of problems was higher 12 years post-injury compared with 12 months post-injury for four of five dimensions. Importantly, the prevalence of problems did not reduce to pre-injury levels for any HRQoL dimension.
Discussion POIS-10 highlights the importance of early post-injury interventions to improve health, disability and well-being outcomes of injured New Zealanders.
- Cohort Study
- Descriptive Epidemiology
- Outcome of Injury
- Disability
- Quality Of Life
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WHAT IS ALREADY KNOWN ON THIS TOPIC
Specific injuries (eg, traumatic brain injury or spinal cord injury) are associated with adverse outcomes for people beyond 24 months.
Little is known about longer-term outcomes among injured people experiencing a diverse range of injury types and severities.
WHAT THIS STUDY ADDS
Ongoing problems attributed to an injury that occurred 12 years ago are prevalent.
High proportions of injured participants reported problems with disability and health-related quality of life 12 years post-injury.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
Internationally, the ‘Prospective Outcomes of Injury Study–10 years on’ (POIS-10) contributes by adding to limited evidence about long-term post-injury outcomes.
In New Zealand, POIS-10 provides unique information to support the Accident Compensation Corporation’s work focused on preventing injury and improving long-term outcomes, including specifically for Māori.
Introduction
In Aotearoa me Te Waipounamu (New Zealand; NZ) between 2020 and 2021, the country’s no-fault universal injury insurer, the Accident Compensation Corporation (ACC), had over 2 million new injury claims and spent almost $6 billion supporting injured people.1 Studies have found adverse outcomes can be experienced up to, and beyond, 24 months post-injury; however, findings have been limited to specific injury types (eg, traumatic brain injury or spinal cord injury)2 or causes (eg, transport accidents).3 Few studies report longer-term outcomes among non-specific injury types.4 5
The Prospective Outcomes of Injury Study (POIS), a longitudinal cohort study, explored injury and health rehabilitation, and social and economic factors leading to disability, health and well-being outcomes at 3, 12 and 24 months after injury among New Zealanders. POIS-10 has followed participants to approximately 10 years since their last POIS interview (ie, 12 years post-injury).6 This short report aims to describe characteristics of the POIS-10 cohort followed to 12 years post-injury and participants’ key disability, health and well-being outcomes.
Methods
Between 2007 and 2009, 2856 POIS participants were recruited via ACC’s entitlement claims injury register, including n=566 Māori.7 ACC entitlement claimants had experienced injuries likely to require earnings-related compensation, or rehabilitation or social supports for their injury. Participants had a range of injury types, causes and settings; 25% were hospitalised for their injury; the injury leading to recruitment to POIS is hereafter referred to as the ‘sentinel’ injury. People experiencing self-harm or sensitive claim injuries (eg, sexual assault) were ineligible. Recruitment continued until 20% of the cohort were Māori.8 Participants completed telephone or postal questionnaires 3, 12 and 24 months post-injury.7
People were eligible for POIS-10 if they had completed a POIS 24-month interview and had agreed to being recontacted by the research team.6 POIS-10 interviewers made up to eight contact attempts (telephone and/or email) to reach potential participants, and if unsuccessful, up to five attempts to reach participants’ previously nominated alternative contacts. ACC also posted study information letters to participants who remained uncontactable and provided researchers with any updated contact details. Electoral rolls were also reviewed to identify updated contact details for eligible past POIS participants.
POIS-10 data were collected between March 2020 and July 2021. Data were primarily collected via structured questionnaires (figure 1) administered via computer-administered telephone interviews by 15 trained interviewers, including te reo Māori (Māori language)-speaking interviewers. Interviews, undertaken 12 years following the sentinel injury, were typically 1 hour in duration.
Overview of POIS and POIS-10 recruitment and data collection. ACC, Accident Compensation Corporation; POIS, Prospective Outcomes of Injury Study; POIS-10, Prospective Outcomes of Injury Study–10 years on.
POIS-10 interview questions asked about sociodemographic characteristics (eg, ethnicity, education, adequacy of household income),9 10 disability,11 health12 13 and well-being 12 years post-injury (table 1).14–16 The WHO Disability Assessment Schedule II (WHODAS II) measured level of difficulty on 12 items using a 5-point scale (ie, none, mild, moderate, severe, extreme), categorised as ‘no’ or ‘any difficulty’ for analyses.11 Health-related quality of life (HRQoL) outcome was assessed using the EQ-5D-5L, with five dimensions: Mobility (MO), Self-Care (SC), Usual Activities (UA), Pain/Discomfort (PD) and Anxiety/Depression (AD); responses on a 5-point scale (eg, no, slight, moderate, severe or extreme problems) were categorised as ‘no problems’ or ‘any problems’.13 Injury recovery was operationalised by a yes/no question personalised to the individual: ‘Do you have any ongoing problems from the injury you had in (year) when you (describe sentinel injury event)?’ The first POIS interview (3 months post-injury) also recalled certain pre-injury sociodemographic, disability, health and well-being characteristics.
Overview of key predictors and outcomes collected in POIS and POIS-10 questionnaires
Administrative injury-related data were obtained, with participants’ consent, from ACC, and for those who were hospitalised for their injury, from the National Minimum Data Set of hospital discharges. These data provided descriptions of the sentinel injury type and cause; allowed derivation of injury severity scores (New Injury Severity Score)17; hospitalisation status and the occurrence of subsequent injury events since recruitment to POIS.
Results
Of the 2856 POIS participants, 2256 (79%) completed a POIS questionnaire approximately 24 months post-injury. Of the 2256, 2068 people (92%) had agreed to future follow-up or were not known to have died (figure 1). Of the 2068 potential POIS-10 interviewees, 1543 (75%) people participated; 1430 (93%) completed a telephone interview and 113 (7%) a paper questionnaire. The main reasons for non-participation were the research team’s inability to trace potential participants (n=360; 17%) or people declining to take part (n=161; 8%). POIS-10 questionnaires were completed 12.2 years (median) after participants’ sentinel injury. Participant characteristics at 12 years post-injury are presented in table 2. The mean age at POIS-10 follow-up was 55 years (range=29–78 years). Most people (72%) were in paid employment, and 74% reported that they had enough, or more than enough, household income to meet their everyday needs. At least one comorbidity was reported by 1207 (78%) participants. There were few missing responses (<1%) for sociodemographic characteristics.
Key characteristics of POIS-10 participants (n=1543) 12 years after sentinel injury
Half the POIS-10 cohort (n=767; 50%) reported experiencing ongoing problems associated with the sentinel injury at 12 years. Many participants (n=651; 42%) also reported being affected by a different (non-sentinel) injury at this time. Proportions reporting disability problems ranged between 9% reporting difficulties maintaining a friendship and 39% reporting difficulties due to being emotionally affected by their health condition/s (table 3). Over one-third of POIS-10 participants (n=569; 37%) reported ‘no difficulties’ with any of the 12 WHODAS II items.11 The majority (57%) of POIS-10 participants reported excellent or very good health overall.12 However, considerable proportions reported experiencing ‘any problems’ with the five EQ-5D-5L dimensions,13 from 13% reporting ‘any problems’ with SC to 54% reporting ‘any problems’ with PD. Just over one-third (n=546; 35%) of POIS-10 participants reported ‘no problems’ with any of the five EQ-5D-5L dimensions. A high proportion of participants (88%) reported overall life satisfaction (mostly or completely satisfied) at long-term follow-up.13 15
Key descriptive disability, health and well-being outcomes 12 years after sentinel injury among POIS-10 participants (n=1543)
Missing responses for key POIS-10 outcomes were low; 0.5% (n=8) were missing responses to all 12 WHODAS II items; 0.5% (n=7) were missing a response to overall health status; 0.3% (n=4) were missing responses to all five EQ-5D-5L dimensions and 0.4% (n=6) were missing a response to the life satisfaction question.
Discussion
This paper describes characteristics of the POIS-10 cohort, including their health, disability and well-being outcomes 12 years after a sentinel injury. Describing the cohort is the first step towards understanding long-term outcomes after injury and identifying opportunities for intervention to improve the health of injured New Zealanders.
Of concern, over two-thirds of the cohort experienced difficulties with disability 12 years post-injury. While over half of POIS participants reported being emotionally affected by their health problems and having difficulty standing for long periods 3 months post-injury,7 over one-third of the cohort reported difficulties on these WHODAS items 12 years on. Also, the majority (78%) of participants reported at least one comorbidity 12 years post-injury. Earlier POIS analyses found pre-injury multimorbidity was associated with an increased risk of disability 24 months post-injury18 19; longitudinal analyses are now underway to explore changes in disability overtime in the cohort and predictors of longer-term disability outcomes.
Regarding HRQoL, the prevalence of ‘any problems’ with UA was slightly lower 12 years after injury for POIS-10 participants (EQ-5D-5L UA=27%) compared with the prevalence reported by participants 12 months post-injury (EQ-5D-3L ‘any problems’ UA=30%), but was higher, or slightly higher, 12 years post-injury for the remaining four EQ-5D dimensions (EQ-5D-5L ‘any problems’: MO=29%, SC=13%, PD=54% and AD=23%) compared with 12 months post-injury (EQ-5D-3L ‘any problems’: MO=24%, SC=7%, PD=52% and AD=20%).20 Importantly, in no EQ-5D dimension did the prevalence of problems approach reported pre-injury levels (EQ-5D-3L ‘any problems’: MO=6%, SC=2%, UA=6%, PD=6% and AD=6%).20
Some of the disability and HRQoL problems experienced 12 years post-injury will be related to ageing and comorbid conditions (78% reported at least one comorbid condition at 12 years, compared with 46% pre-injury); nevertheless, such a high proportion reporting ongoing problems associated with their sentinel injury is important in terms of timely interventions to improve outcomes. Despite the prevalence of disability and HRQoL problems, a high proportion of participants (88%) reporting overall life satisfaction 12 years after injury is encouraging. The exclusion of injuries resulting from self-harm or sensitive claims (eg, sexual assault) means the prevalence of life satisfaction may be overestimated, while anxiety/depression may be underestimated in POIS-10 compared with the ‘all injury’ population in NZ. A further limitation of this study is that our findings are likely to have been biased by participants lost to follow-up. To assess this, we ran a sensitivity analysis under the extreme case scenario assuming that all potential participants lost to follow-up had no post-injury difficulties. Under this hypothetical scenario, the prevalence of estimated difficulties would reduce by 25%.
POIS-10 is unique in its recruitment of New Zealanders with a range of injury types and follow-up to 12 years post-injury. Conducting interviews using a highly structured questionnaire resulted in the collection of a rich data set, with low proportions of missing responses. We believe the completeness of data is largely due to the skilled interviewers, and their ability to develop rapport and sustain engagement with participants throughout the hour-long interview. The skilled interviewers and rigorous contact tracing processes also enabled POIS-10 to achieve its aspirational follow-up rate (75% of those eligible).6
Conclusions
Twelve years post-injury, many participants experienced ongoing problems attributed to their sentinel injury. Almost two-thirds of participants reported difficulties with disability and/or HRQoL problems. Problems with pain or discomfort were most common. By identifying long-term outcomes after injury, POIS-10 findings highlight the importance of early post-injury interventions and contribute towards understanding the health, disability and well-being needs of injured New Zealanders, especially for Māori.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by New Zealand’s Southern Health and Disability Ethics Committee (MEC/07/07/093/AM07). Participants gave informed consent to participate in the study before taking part.
Acknowledgments
The authors wish to thank the POIS and POIS-10 participants for their participation over many years. They thank the skilled team of POIS-10 interviewers for the care they took in data collection. They also thank the Health Research Council of New Zealand for funding POIS-10 and the University of Otago for hosting this research.
Footnotes
Contributors SD and EHW are principal investigators of POIS-10 and conceived the idea for the study. AS and HH are named investigators on POIS-10. HEO is the POIS-10 operational project manager; DB the data manager, and BM is undertaking various analyses. SD and HEO prepared the first draft of the paper. HEO, DB and BM collated the descriptive data, and all authors reviewed the initial and final drafts of the paper.
Funding This research was funded by the Health Research Council of New Zealand (2019–2022; HRC19/344).
Disclaimer The views and conclusions in the article are the authors' and may not represent those of funders.
Competing interests SD is a member of the EuroQol Group responsible for the development of the EQ-5D instruments used in this study; no funding was received from the EuroQol Group for the POIS-10 Study reported in this short report. Other authors indicate they have no competing interests to declare.
Patient and public involvement statement Consultation about the design of POIS was undertaken with people living with an injury-related disability and Māori stakeholders prior to the commencement of POIS. Patients and/or the public were not involved in the conduct, reporting or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.