School of PsychologyFACULTY OF MEDICINE AND HEALTH

Improving health information to promote health literacy

Factors influencing the perception of side effect risk information – reflections and

prospects for research

Peter GardnerSenior Lecturer and Head of School

School of Psychology

p.h.gardner@leeds.ac.uk

Patient Information Leaflets (PILs)

Getting better…?

Which parts of the leaflet do people read?

Side effects 96%

How and when to take it 91%

What is your medicine for? 85%

Things to do before you take 66%

What is in your medicine? 53%

MORI Survey for Medicines Partnership, 2003, 2004

Ask about Medicines Week

Testing the EU terms

EU People

Very common > 10% 54%

Common 1 - 10% 34%

Uncommon 0.1 - 1% 11%

Rare 0.01 - 0.1% 8%

Very rare < 0.01% 4%

Knapp, Raynor, Berry (2004) Quality & Safety in Health Care.

Berry, Knapp, Raynor (2002) Lancet.

What about online Information?

Using a pop-up on a medicine page of Cancerhelp.org.uk

(now ‘About Cancer’ pages)

• 8 on-line studies since 2004• Publications in British Journal of Health Psychology, Drug Safety, Patient Education

and Counseling, Health Expectations.

• Tested alternative formats for presenting side effect risk on perceptions of risk

• Controlled design with random allocation

• Taxol, Ibuprofen, Tamoxifen

• Approximately 15 participants per month

• Participants more likely to have a personal interest

Cancer Research UK studiesBackground

• Broadly, the suite of studies have tested the effect of stating the risk of side effects as verbal descriptors, percentages and frequency statements and combinations of these formats.

• Started off with the premise that ‘Natural Frequencies’ are more concrete and would probably work better

• e.g. If 100 people took this medicine, 3 would get constipation.

Cancer Research UK studiesFindings

• The evidence suggests that verbal descriptors (“common”/ “rare”) on their own produce markedly less accurate estimations of risk

• Percentages generally perform well, but some evidence that these are not so good for low risks

• More specific statements about frequency show some superiority over frequency bands (“affects more than 1 in 10 patients”) but may not be so feasible

• People prefer combined statements (“affects 1 in 500 people (0.2%)”) but are no more accurate in their estimation of risk

Cancer Research UK studiesImpact

Cancer Research UK studiesLatest study

Testing EMA recommendations

• EMA requires a combination of words and frequency bands

Common: may affect up to 1 in 10 people

• NICE suggest that verbal descriptors should not be used without numerical information

• It could be argued that these recommendations are on the basis of consensus, not evidence

Testing EMA recommendations

• Two questions:• Does the use of the verbal descriptor ‘frame’ patients’

understanding leading to overestimation of risk?

• Does the use of two indicators of uncertainty lead to confusion?

‘may affect’ and ‘up to 1 in 10’

• Compare with

‘will affect’ and ‘up to 1 in 10’

Testing EMA recommendations

• 2 x 2 factorial design• Numerical format vs. Combined verbal and numerical

• ‘will affect’ vs. ‘may affect’

• Presented with information on 10 potential side effects; 2 each from the 5 EC frequency bands

• Asked to provide risk estimates for 5 of the side effects; 1 from each of the bandings

Scenario

Testing EMA recommendations

• 339 participants• Numerical + may = 91

• Combined + may = 85

• Numerical + will = 77

• Combined + will = 86

Participants

Testing EMA recommendations

• Asked to provide risk estimates for 5 of the side effects; 1 from each of the bandings and a rating of the perceived risk of experiencing ANY of the side effects

• Also completed 5 Likert scales regarding:• Satisfaction with the information

• Severity of the side effects

• Likelihood of experiencing a side effect

• General risk to health

• Effect on decision to continue treatment

ResultsNumerical vs. Combined

Results

• No differences between ‘may’ and ‘will’ conditions on perceptions of side effect risk

• Little difference in Likert ratings between the conditions• Higher perceived likelihood of experiencing side effects in the

combined condition

• No evidence of interactions between the variables

Results‘May’ vs. ‘Will’

Conclusions

• Possible framing effect of verbal descriptors

• Variability of response suggests lack of shared understanding of risk descriptions

• Problem of overestimation still prevalent in ‘numerical only’ condition, but…• Low incidence rates mean that people are more likely to

overestimate than underestimate

• Heterogeneity of risk perception responses may mean it is impossible to get shared understanding

• Precise risk information is difficult to obtain anyway

Future research

• Need for replication of findings with different medicines

• Are there other factors involved?• Numeracy (see Gardner et al, 2011)

• Other individual differences

• Emotional reaction to different types of treatment

• Need to investigate the effect on actual behaviour

References

Berry, D.C., Knapp, P. and Raynor, D.K. (2002). Provision of information about drug side effects to patients. Lancet, 359, 853-4.

Gardner, P.H., McMillan, B.R.W., Raynor, D.K., Woolf, E., Knapp, P. (2011). The effect of numeracy on the comprehension of information about medicines in users of a patient information website. Patient Education and Counseling, 83, 398-403.

Knapp, P., Gardner P.H., Carrigan N., Raynor, D.K. and Woolf, E. (2009). Perceived risk of medicine side effects in users of a patient information website: a study of the use of verbal descriptors, percentages and natural frequencies. British Journal of Health Psychology,14, 579-94.

Knapp, P., Gardner, P.H., Raynor, D.K., Woolf, E. and McMillan, B.R.W. (2010). Perceived risk of Tamoxifen side effects: a study of the use of absolute frequencies or frequency bands, with or without verbal descriptors. Patient Education and Counseling, 79(2), 267-271.

Knapp, P.R., Gardner, P.H. and Woolf, E. (2015). Combined verbal and numerical expressions increase perceived risk of medicine side-effects: a randomized controlled trial of EMA recommendations. Health Expectations, published online 26 Jan 2015, doi: 10.1111/hex.12344.

Knapp, P., Raynor, D.K. and Berry, D.C. (2004). Comparison of two methods of presenting risk information to patients about the side effects of medicines. Quality and Safety in Health Care,13, 176-80.

Knapp, P., Raynor, D.K., Woolf, E., Gardner, P.H., Carrigan, N. and McMillan, B.R.W. (2009). Communicating the risk of side effects to patients: an evaluation of UK regulatory recommendations. Drug Safety, 32(10), 837-849.