ESPEN Congress Copenhagen 2016

Transcription

1 ESPEN Congress Copenhagen 2016 BUILDING EVIDENCE IN CLINICAL NUTRITION- HOW TO DO WITHOUT RANDOMIZED CONTROLLED TRIALS GOOD EVIDENCE FOR PATIENT CENTRED NUTRITION INTERVENTION C. Baldwin (UK)

2 Good evidence for patient-centred nutritional intervention? Dr Christine Baldwin King s College London (No conflicts of interest to declare)

3 Learning outcomes To understand the different types and levels of evidence To understand the advantages and disadvantages of each To introduce ways to evaluate study quality

4 Patient-centred nutritional interventions Definition: An intervention which considers individual patient preferences, needs and values Clinical question: Will a patient-centred intervention in nutritionally vulnerable people improve outcome more than routine care?

5 Types of study design Is random assignment used? Yes No Randomised controlled trial (RCT) Is there a control group or multiple measure? Yes No Quasiexperimental Non-experimental One group design pre-test/post-test interrupted time series (ITS) Two group design pre-test/post-test, ITS cohort study case-control study

6 Cross-sectional studies Involves the collection and analysis of data from a population or representative sample at one specific point in time Strengths Suggest association Hypothesis-generating Useful in healthcare planning (assess disease burden in a population) Weaknesses Difficult to infer causality Confounding (alternative explanations) Sample selection Recall bias

7 Cross-sectional studies: colorectal cancer and meat intake Age-standardised rate of colorectal cancer increases as the meat consumption of a population increases

8 Cross-sectional studies: malnutrition and survival Andreyev HJN et al., Eur J Cancer (1998) 34:

9 Types of study design Is random assignment used? Yes No Randomised controlled trial (RCT) Is there a control group or multiple measure? Yes No Quasiexperimental Non-experimental One group design pre-test/post-test interrupted time series (ITS) Two group design pre-test/post-test, ITS cohort study case-control study

10 Randomised controlled trials (RCT): example Female patients (n=318) with hip fracture who received conventional care + additional support from dietetic assistants vs conventional care only Outcomes assessed: mortality (post-op & 4 months), LOS, complications, nutritional status, energy intake Significant benefits No difference Mortality (post-op & 4 months) Energy intake MAC LOS Complications Other aspects of nutritional status Duncan DG et al., Age & Ageing (2006) 35:

11 Randomised controlled trials (RCT) Participants are randomly assigned to groups (usually intervention and control) and receive (or not) an experimental intervention Infer causality Strengths Gold standard for evaluating effectiveness of interventions Weaknesses Cost of selection and randomisation of participants Feasibility of recruitment and sample size needed Conclusions might be limited to the dose and population studied Application to the clinical setting may be limited

12 Types of study design Is random assignment used? Yes No Randomised controlled trial (RCT) Is there a control group or multiple measure? Yes No Quasiexperimental Non-experimental One group design pre-test/post-test interrupted time series (ITS) Two group design pre-test/post-test, ITS cohort study case-control study

13 One group experimental designs: pre-test/post-test Pre-test Intervention Post-test

14 Pre-test/post-test: example Consecutive admissions >65 years old (n=254) in various clinical conditions Interventions: assistance at meals, protected mealtimes or both together Outcomes assessed: mealtime assistance, mealtime interruptions, activities of nursing staff, nutritional intake Significant benefits Mealtime assistance (30% vs 76-80%, p<0.01) Non-clinical nursing tasks (66% vs 27-36%, p<0.01) No difference Mealtime interruptions Nutritional intake Young AM et al., Clin Nutr (2013) 32:

15 Pre-test/post-test: design Participants are assigned to groups without randomisation Strengths Easier to set up than RCTs Less impact on the clinical environment May remove or reduce ethical concerns Maturation History Seasonality Attrition Weaknesses

16 One group experimental design interrupted time series X-X-X X-X-X X-X-X Prior to intervention During intervention After intervention

17 Interrupted time series: example Anaby D et al., Physical & Occupational Therapy In Pediatrics (2014) 34:

18 Types of study design Is random assignment used? Yes No Randomised controlled trial (RCT) Is there a control group or multiple measure? Yes No Quasiexperimental Non-experimental One group design pre-test/post-test Interrupted time series (ITS) Two group design pre-test/post-test, ITS cohort study case-control study

19 Two group experimental designs Pre-test/post-test Interrupted time series Strength Comparison between individuals Weakness Sample selection

20 Cohort studies Study population Exposure is self-selected Malnourished Not malnourished Follow through time Experience the outcome Don t experience the outcome Experience the outcome Don t experience the outcome

21 EuroOOPS Used NRS hospital departments across Europe Fixed number of patients recruited and followed up for 28 days Sorensen J et al., Clin Nutr (2008) 27:

22 5,051 patients EuroOOPS results At nutritional risk = 33% (range %) at nutritional risk not at risk Developed complications 31% 11% Length of hospital stay (days) 9 (5-16) 6 (3-11) Mortality 12% 1% Discharge destination: Home Hospital Nursing home 60% 24% 4% 88% 10% 2% Sorensen J et al., Clin Nutr (2008) 27:

23 Cohort studies Compare incidence of the outcome in patients exposed to the condition (eg malnutrition) with patients not exposed to the condition Strengths Allows calculation of incidence Examination of multiple effects of an exposure Avoids selection bias Weaknesses Confounding by other variables (residual confounding) Misclassification of the exposure (nutritional status) or outcome Attrition

24 Association between nutrition-related parameters and prolonged length of hospital stay Allard JP et al., J Parenter Enteral Nutr (2015) 40:

25 Case-control studies

26 Case-control studies Compares an exposure (ie diet) in patients with the disease (cases) with a group of people without the disease (controls) from the same population Strengths Efficient for rare diseases Less expensive and time consuming than cohort studies Useful when studying dynamic populations Weaknesses Selection of controls (selection bias) Dietary data collected retrospectively (reporting bias) Effect of disease on diet (misreporting habitual past diet?)

27 How to evaluate study quality

28 Assessing risk of bias in studies Domain Sequence generation Allocation concealment Blinding of participants, personnel and outcome assessors Incomplete outcome data Selective outcome reporting Other sources of bias Description Method used to generate the random sequence Method used to conceal allocation Methods used to blind different aspects of the study Reports all outcomes and attrition Are all study outcomes reported? (check protocol) Eg. imbalances in groups at baseline Critical appraisal tools: Critical Appraisal Skills Programme - Scottish Intercollegiate Guidelines Network -

29 Levels of evidence (ESPEN) Schütz T et al., Clin Nutr (2006) 25:

30 Levels of evidence (Australia) Merlin T et al., BMC Medical Research Methodology (2009) 9:34

31 Final thoughts: are other study designs comparable to RCTs? 106 reports of therapeutic studies Included if >2 RCTs and historical controlled studies (HCT) on the same therapy Trial type Benefit from therapy No benefit from therapy RCT (n=50) HCT (n=56) Sacks H et al., Am J Med (1982) 72:

32 Final thoughts: are other study designs comparable to RCTs? Benson K et al., N Engl J Med (2000) 342:

33 Take home messages Well conducted, non-randomised trials can be comparable to RCTs Apply a flexible approach, where the weight of evidence is determined by appraisal of the characteristics of that evidence