Thesis title: "Cost of illness due to back pain in older people. Healthcare utilization, modifiable prognostic factors, and the measurement properties of self-reported productivity loss using the iMTA Productivity Cost Questionnaire."
Trial lecture title: "From research idea to implementation: the relevance of study design and methods."
Ordinary opponents:
- First opponent: Associate Professor, Paul Enthoven, Linköping University, Sweden
- Second opponent: Researcher, Karin Magnusson, Norwegian Institute of Public Health, Norway
- Leader of the evaluation committee: Associate Professor, Therese Brovold, OsloMet
Leader of the public defense is Professor, Jonas Debesay, OsloMet.
The main supervisor is Professor Margreth Grotle, OsloMet and the co-supervisor is Adjunct Professor, Kjersti Storheim, OsloMet.
Thesis abstract
Back pain imposes substantial individual and societal costs, and with an aging population and an increasing number of older people with back pain, these costs are likely to increase in the years to come.
To improve the use of scarce healthcare resources and reduce the economic burden on our healthcare systems, it is vital to map healthcare utilization and related costs and identify modifiable prognostic factors of the high costs related to healthcare utilization.
No such studies have been conducted among a sample of exclusively older people, although the prevalence of seeking healthcare for back pain increases with age.
Furthermore, to promote comprehensive healthcare economic evaluations, there is a need for valid generic instruments for measuring productivity costs. Productivity costs often reflect a large part of total costs related to health and healthcare interventions.
Aims
The primary aim of this thesis was to develop new knowledge on the cost of illness due to back pain among older people, to describe healthcare utilization and estimate associated costs among older people seeking primary care due to back pain (Paper I) and to identify modifiable prognostic factors of high costs related to healthcare utilization (Paper II).
A secondary aim was to evaluate the measurement properties of the iMTA Productivity Cost Questionnaire (iPCQ) (Papers III and IV).
Methods
Papers I and II were conducted using a cohort study design with one-year of follow-up.
Data from the Back Complaints in the Elders (BACE) consortium in Norway (BACE-N) and the Netherlands (BACE-D) were used.
BACE-N included 452 people aged ≥ 55 years seeking Norwegian primary care with a new episode of back pain, and BACE-D included 675 people aged >55 years seeking Dutch primary care with a new episode of back pain.
In Paper I, healthcare utilization and related costs were described for the whole BACE-N sample as well as for patients with different risk profiles according to the STarT Back Screening Tool (SBST).
In Paper II, potential modifiable prognostic factors of high costs related to healthcare utilization were identified in BACE-N, and the findings were then replicated in BACE-D.
In Papers III and IV, the content validity, construct validity, criterion validity, and test-retest reliability of the iPCQ were evaluated in two different Norwegian samples.
Paper III was a cross-sectional study, including a test-retest assessment, of 115 patients with musculoskeletal disorders referred to an outpatient rehabilitation clinic.
Paper IV was a cross-sectional study, including one year of retrospective public registry data on absenteeism, among 144 people who had been on sick leave for at least four weeks due to musculoskeletal disorders.
Main results and conclusions
In Paper I, the one-year mean and median total cost per patient were estimated at €825 and €364, respectively.
The largest cost category was primary care consultations (56 percent of total costs). Imaging rate was 34 percent. A total of 34-45 percent of patients used medication, and the most widely used type was paracetamol (27-35 percent of patients).
Patients with medium and high risk of persistent disabling back pain according to the SBST had a significantly higher degree of healthcare utilization compared to patients with low risk.
In Paper II, four modifiable prognostic factors associated with high costs related to healthcare utilization were identified and replicated: a higher degree of pain severity, disability, and depression, and a lower degree of physical health-related quality of life.
In Paper III, the content validity of the iPCQ was found to be sufficient, construct validity was confirmed, and test-retest reliability was acceptable.
In Paper IV, self-reported productivity loss by the iPCQ showed good agreement with public registry data regarding the occurrence and duration of long-term absenteeism.
However, the iPCQ does not cover part-time sick leave and overestimated the number of days with complete absenteeism with median 17 days.
Implications
This thesis provides knowledge that can be used to inform the use of scarce healthcare resources and reduce the economic burden of back pain on healthcare systems.
Decreasing the use of imaging and paracetamol seem to be important areas for quality improvement in primary care management of older patients with back pain.
In addition, pain severity, disability, depression, and physical health-related quality of life are potential target areas for interventions directed towards reducing high costs related to healthcare utilization among these patients.
Moreover, this thesis contributes knowledge useful for conducting comprehensive health economic evaluations which include productivity costs.
The iPCQ can be recommended as a useful tool for measuring three important components of productivity costs among people with musculoskeletal disorders: absenteeism, presenteeism, and costs related to unpaid work.
