| Literature DB >> 27100402 |
Kristen Pickles1, Stacy M Carter1, Lucie Rychetnik2, Kirsten McCaffery3, Vikki A Entwistle4.
Abstract
BACKGROUND: Prostate-specific antigen (PSA) testing for prostate cancer is controversial. There are unresolved tensions and disagreements amongst experts, and clinical guidelines conflict. This both reflects and generates significant uncertainty about the appropriateness of screening. Little is known about general practitioners' (GPs') perspectives and experiences in relation to PSA testing of asymptomatic men. In this paper we asked the following questions: (1) What are the primary sources of uncertainty as described by GPs in the context of PSA testing? (2) How do GPs experience and respond to different sources of uncertainty?Entities:
Mesh:
Year: 2016 PMID: 27100402 PMCID: PMC4839572 DOI: 10.1371/journal.pone.0153299
Source DB: PubMed Journal: PLoS One ISSN: 1932-6203 Impact factor: 3.240
Sources of uncertainty (where is GP uncertainty coming from?).
| Han’s SOURCES of uncertainty | How does this taxonomy manifest in the context of PSA testing? |
|---|---|
| Several important potential outcomes may follow from PSA testing. Early diagnosis and treatment may decrease prostate cancer death for a small number of men. For the majority, any mortality benefit is outweighed by risk of harm: testing and treatment is associated with substantial harms, including impotence, incontinence, and anxiety. Although the probabilities of some of these outcomes can be estimated for populations, there is no way of knowing which individual patient will experience which outcomes. | |
| The PSA test performs poorly as a screening tool. It is known that some screen-detected prostate cancers are more aggressive than others, but the PSA test cannot differentiate aggressive from non-aggressive cancers. This, together with uncertainties about treatment effects, uncertainty about how particular patients might react to different biomedical clinical outcomes (physically and psycho-socially), and how patients may respond differently to the risk of these outcomes, means it is unclear what test results might actually mean for each individual patient both at the point of testing and following an abnormal test result | |
| The multiple-stage, multiple possibility sequence of testing and treatment outlined above add complexity to an evaluation of testing. Although the patient descriptors used in research studies and guidelines may seem simple (e.g. age 70+, asymptomatic) in general practice many individual patients are complex in ways not reflected in the evidence base. This includes the presence of comorbidities, and the difficulty in distinguishing symptomatic from asymptomatic men because of the multiplicity of causes of the symptoms commonly associated with prostate cancer. GPs consequently feel uncertain about how clinical descriptors should be applied. |
Issues of uncertainty (what is the uncertainty ABOUT?).
| Han’s ISSUES of uncertainty (what is the uncertainty about?) | Probabilistic material as a Source of uncertainty (uncertainty arising from the probabilistic nature of information) | Ambiguity as a Source of uncertainty (uncertainty arising from the ambiguity of evidence or expert guidance): | Complexity as a Source of uncertainty (uncertainty arising from the interaction of multiple factors, some unknown): |
|---|---|---|---|
| • GPs concerned about their inability to predict clinical outcomes (such as incontinence or impotence) following testing and treatment at the individual patient level. Probabilities can predict aggregate outcomes in a population, but cannot specify their exact distribution, or the probable severity of potential outcomes in any given individual. | • GPs concerned about conflicting estimates for particular outcomes for particular populations GPs uncertain about the conclusions that should be drawn from the evidence base for/against screening for prostate cancer | • Interpretation of the benefits and risks of testing and treatment can change over time and depend on various assumptions (e.g. about patient values and current state). GPs concerned about evaluating benefits and risks and making treatment decisions relating to individual patients because of this complexity. | |
| • GPs described probabilities as challenging to think about and apply in individual clinical encountersGPs unsure how urologists will work with patients referred with a high PSA result | • GPs uncertain about professional practice due to disagreement between guidelines GPs concerned about conflicting guidance from medical authority: professional organizations and colleagues vary in the recommendations they make about whether or not (and under what circumstances) to screen with PSAGPs unclear under what conditions they could be medically liableGPs concerned about inconsistent referral pathways and advice | GPs find communicating probabilistic information with specific patient types (e.g. health illiterate, anxious, determined to have the test) difficultGPs seeing a patient who usually consults a different GP found this a complex and ‘awkward’ situation in which to practice if their testing preferences were dissimilar to the GP they were replacing | |
| GPs concerned about their inability to predict the psychological and existential outcomes of testing and treatment that would be experienced by the patient | • GPs consider what is at stake for them as an individual clinician—legally, psychologically, professionally and socially—if they do or do not testGPs uncertain about what is the right thing to do in this context in order to be considered a ‘good GP’ and preserve relations with their patientsGPs concerned about whether it is ok to change PSA testing practice following personal and practice experiences | • GPs concerned about their ability to judge how ‘good’ any individual patient’s consent/decision might be, and what the outcomes of poor/inaccurate judgment may mean for them and their patientsGPs uncertain about individual patient tolerability of potential consequences of their decisionsGPs feel conflicted when their own personal preferences for testing/not testing conflict with advice they provide |