Epidemiological and other research designs

Transcription

1 WHO Collaborating Centre for Palliative Care & Older People Epidemiological and other research designs Irene J Higginson, Cicely Saunders Institute, Department of Palliative Care, Policy & Rehabilitation, King s College London

2 Outline Epidemiology Overview of designs Examples to study access and care delivery (effects on older people, culture) Cross sectional (especially analysis of large data sets) Cohort Quasi-experimental Randomised trial Summary and references

3 Epidemiological research Epidemiology is concerned with patterns, frequency and cause of illness and diseases (including symptoms Epidemiological information is used to determine needs and to plan and evaluate the provision of healthcare and other services. It can assess accessibility, effectiveness, efficacy, efficiency, acceptability

4 Types of Study - Main classes Observational (Non-experimental) - observe something that naturally occurs and often test for associations between variables (cross sectional, cohort) Quasi-experimental acts as if experiment but not random allocation Experimental studies - test the effectiveness or efficacy, of a treatment or intervention Clinical audit methods

5 Cross-sectional studies Make measurements at one point in time (or over a short period) Information can be used to study relationships between variables e.g. age and place of death Can collect data (e.g. via a survey) or use routinely collect data (e.g. death registrations) Can be on individual patients, or groups of patients (ecological study) Can never be causal as the data is collected at the same time

6 Cross sectional survey of fear of dying among ethnically diverse groups Interviews with people over 65 years in two national surveys (n=589, n=400) Data-sets merged, regression Over 7 in 10 of ethnically diverse sample aged 65+ expressed extreme fears of dying Only 4 in 10 of ethnically homogeneous sample had same fears Higher quality of life had protective effect against fears Bowling A, Iliffe S, Kessel A, Higginson IJ. Postgrad Med J 2010;86(1014): www. kcl. ac. uk/ pal l i at i ve

7 Can use cross sectional data to explore different stage of illness e.g. psychological concerns Gao et al, European J Cancer 2010 www. kcl. ac. uk/ pal l i at i ve

8 percentage deaths www. kcl. ac. uk/ pal l i at i ve Individual cross sectional data on place of death among oldest people - Percentage of cancer deaths in each place of death by age cohort (N=307,613) (1995-9, E&W) Home Hospice Care home Hospital age cohorts Source: Lock and Higginson, BMC Palliative Care 2005, 4:6

9 Percent www. kcl. ac. uk/ pal l i at i ve Differences for older people in home deaths London and New York (cross sectional data) 30 Figure 1. Proportion of Cancer Deaths at Home, London New York City Age Decker & Higginson Eur J Pub Health 2007; 17:

10 Ecological study: variation in place of death in small areas % Home cancer deaths vs. deprivation score North Thames, Higginson et al J Pub Health Med 1999

11 Longitudinal (also called cohort) studies Subjects followed over time with continuous or, usually, repeated monitoring of symptoms. Can vary enormously in their size and complexity. At one extreme could study a large group (or cohort) of patients, repeatedly, from diagnosis to death. At the other extreme, a small number of patients (a small cohort) could be followed for a few days or weeks.

12 Examples cohort / longitudinal studies

13 Retrospective cohort study Analysis of administrative data collected on health service use during care Examined relationship between age and use of palliative care programme (PCP)

14 QUASI-EXPERIMENTAL STUDIES = a study in which an intervention is deliberately introduced to observe its effects (the artificial manipulation of the study factor) without using randomisation to create the comparisons from which the effects are inferred. tests the efficacy (or the effectiveness) of an intervention, in a quasi-experimental study the intervention can be planned by the investigators (that implement the intervention themselves in a group of subjects or in a specific area), or can be planned by others not directly involved in the study

15 Types of quasi-experimental studies One-group posttest only design (weakest) Intervention Assessment One-group pretest-posttest design (before and after study) Assessment Intervention Assessment

16 Time series (stronger) Repeated assessments (A) before and after intervention, so trends can be studies, and separated from the effect of the intervention A A A A A A A A A Intervention

17 pretest-posttest with external control group design (stronger) EXPERIMENTAL GROUP Assessment Intervention Assessment CONTROL GROUP Pain assessment Intervention Pain assessment

18 Evaluation of hospice day care using three groups before day care opened (while it was being built) received day care and comparison group who did not have day care (by choice or distance) Patients entering day care were using higher levels of services and had higher levels of need (as measured by POS) Little difference in change in service use, slightly greater reduction in day care group www. kcl. ac. uk/ pal l i at i ve

19 Experimental designs: RCT www. kcl. ac. uk/ pal l i at i ve

20 Clinical audit / clinical databases, descriptive studies and surveys Collect data on a more representative group of patients Identify strengths and weaknesses Cannot test cause and effect but in reality can often highlight areas where these should be tested and data can be modelled to explore cause

21 Example: Interval between first palliative care consult and death in patients diagnosed with advanced cancer at a comprehensive cancer centre. Determined interval between first palliative care consult (PC1) and death (D) in cancer patients at comprehensive cancer center and whether interval has increased over time consecutive patients who had their PC1 during a 30- month period. Reviewed the charts for information Median PC1-D interval was longer in patients with solid tumors (p < ), less than 65 years old (p = 0.002), and females (p = 0.004). The median PC1-D interval in 5 consecutive half-years was 46, 56, 42, 41, and 34 days, respectively (p = 0.02). The first palliative care consultation to death interval has decreased over time Osta BE, Palmer JL, Paraskevopoulos T, Pei BL, Roberts LE, Poulter VA, Chacko R, Bruera E. J Palliat Med Jan-Feb;11(1):51-7.

22 Summary and references Epidemiological methods very useful in helping to determine access and evaluate services Range of methods available Observational, quasi-experimental, experimental Costantini M, Higginson IJ. Experimental and quasi-experimental designs. Research Methods in Palliative Care Oxford: Oxford University Press. 2007;pp85-97 Bowling A, Iliffe S, Kessel A, Higginson IJ. Fear of dying in an ethnically diverse society: cross-sectional studies of people aged 65+ in Britain. Postgrad Med J 2010;86(1014): Higginson IJ, McCrone P, Hart S, Burman R, Silber E, Edmonds P. Is Short-Term Palliative Care Cost-Effective in Multiple Sclerosis? A Randomized Phase II Trial. Journal of Pain & Symptom Management 2009, 38(6):

23 Cicely Saunders Institute (London) Inst i t ut e of Pal l i at i ve Care