A pre-post study testing a lung cancer screening decision aid in primary care

Lung cancer is the leading cause of cancer death in the United States (US) [1]. The National Lung Screening Trial (NLST) showed that annual low-dose computed tomography (LDCT) can reduce mortality from lung cancer in a high-risk population [2]. However, despite evidence for mortality reduction, LDCT screening can also lead to harms. For example, more than 95% of screen-detected nodules are ultimately determined to be benign (i.e. false positives) after follow-up evaluation, which can be costly and invasive [2]. Further, screening can also lead to the detection and unnecessary treatment of cancers that would not have affected the patient clinically in his/her lifetime (overdiagnosis) [3, 4].

Based on NLST findings and other evidence [5, 6], the US Preventive Services Task Force (USPSTF) found that there was sufficient support for the net benefit of screening to recommend annual screening with LDCT for patients ages 55–80 with 30 or more pack-years smoking history who have smoked in the past 15 years [4]. Because of the tradeoffs between benefits and harms involved, guidelines recommend a thorough process of informed and shared decision-making occur prior to commencing annual screening. [4, 7] However, experts remain concerned that widespread implementation of screening could happen without patients being appropriately informed [8]. These concerns are supported by accumulating evidence that US patients generally overestimate the benefits and are poorly informed about the potential harms of cancer screening [9–14]. These concerns informed a 2015 Centers for Medicare & Medicaid Services (CMS) coverage decision requiring that a “shared decision-making visit” involving the use of a patient decision aid be conducted before screening would be covered for CMS beneficiaries [15, 16].

Decision aids are evidence-based tools designed to facilitate informed and shared decision-making about complex treatments or screening choices [17]. A lung cancer screening decision aid may be a helpful adjunct in conveying the complex information about benefits and harms of screening. However, few lung cancer screening decision aids have been tested and, to our knowledge, none have been studied in a primary care setting, where cancer screening decisions typically take place [18–20]. Moreover, little is known about whether decision aids help screening-eligible patients develop a realistic understanding of the likelihood of benefitting from screening or improve their understanding of important but difficult to understand screening-related harms, such as false positives and overdiagnosis [18, 19].

We report the findings from a single-group primary care clinic-based study of a video decision aid on lung cancer screening in a cohort of screening-eligible primary care patients. We had three main study aims: first, to assess the effect of the decision aid on knowledge of the benefits and harms of screening and on screening preferences; second, to describe screening behavior within 3 months of viewing a screening decision aid; and third, to examine relationships between screening knowledge, preferences, and screening test ordering during subsequent primary care encounters.

Intervention

We previously developed and refined the decision aid based on feedback from screening-eligible patients from the community (n = 11) and providers from the academic medical center (n = 11) [21]. The decision aid was designed to meet requirements specified by CMS and relevant standards set by the International Patient Decision Aid Standards Collaboration, and to be accessible to those with low literacy [15, 22]. Written text was read aloud, and technical terms and concepts were explained using narration, graphics, and animations. We pre-tested the decision aid and measures with 10 screening-eligible participants before beginning the pre-post phase of the study.

Content included the rationale for screening, eligibility criteria, a description of the LDCT procedure, and a dynamic icon array (pictogram) that sequentially depicted estimates for benefits and harms of screening among 1000 individuals screened annually for 3 years (Fig. 1). Estimates were based on NLST trial data as presented in materials developed by the National Cancer Institute and the Veterans Health Administration (VHA) [2, 20, 23, 24]. Benefits presented in the pictogram were lung cancer deaths averted (3 per 1000 screened). Harms presented included false positives, need for biopsy that did not find cancer, serious complications from biopsies, and overdiagnosis. Other potential screening harms, presented qualitatively (not in the pictogram) included radiation exposure, anxiety and distress, and costs related to follow-up tests and procedures. The video concluded with an implicit values clarification exercise prompting the viewer to weigh the potential benefits and harms of screening and discuss them with his/her doctor. Participants viewed the 6-min video at the clinic on a tablet computer (available online https://goo.gl/1f7XIY).

We report findings from testing a lung cancer screening decision aid in 50 primary care patients. We found that decision aid viewing was associated with greater knowledge of the benefits and harms of screening. At baseline, we found that participants tended to greatly overestimate the chances of benefitting from screening. After viewing, participants tended to have a more realistic understanding of the chances of benefitting. We also found that decision aid viewing led to improved understanding of two important but conceptually complex screening-related harms: false positives and overdiagnosis. To our knowledge, this study is the first to demonstrate that viewing a decision aid can help attenuate biased perceptions about the benefits and harms of lung cancer screening.

Our study complements and extends a limited body of empiric evidence about lung cancer screening decision aids. Previous studies were conducted in populations recruited from the community [19], or referral settings such as a tobacco cessation clinic [18] or a dedicated, sub-specialty screening program [20]. Our study was conducted in a primary care setting and allowed providers to exclude patients they believed to be poor screening candidates based on co-morbidity concerns. Thus, despite being relatively small, our study mimicked a systematic, practice-based approach to screening. Furthermore, two of three prior studies tested lung cancer screening decision aids in mixed populations that included relatively small numbers of screening eligible patients (n = 14 and n = 11, respectively) [18, 19]. All participants in our study were eligible for screening based on current USPSTF guidelines.

We found that baseline (pre-decision aid) screening preferences were heterogeneous, with roughly half of participants falling into each of our two preference groups (preferring screening vs. not). Although decision aid viewing was not associated with net changes in the proportions in each of these preference groups in the overall study sample, about one-quarter of participants in each group actually changed their screening preference after decision aid viewing (in opposite directions). Our findings suggest that we cannot assume screening-eligible primary care patients will be uniformly inclined toward or away from screening. Moreover, our results also suggest that a non-trivial proportion of primary care patients may change their preferences as they become more informed about screening.

Our results are consistent with the findings of Kinsinger et al.’s VHA pragmatic screening demonstration pilot [29] in that we observed heterogeneity in screening behavior. Among participants who preferred screening and saw a provider within 3 months of decision aid viewing, about half discussed LDCT scanning with their provider and about a third completed an LDCT. We also found that some participants who did not prefer screening after decision aid viewing ended up completing an LDCT. Kinsinger et al. similarly found that 50% of eligible patients completed screening [29]. While the VHA demonstration program developed and utilized paper-based decision support materials (from which we adapted our video decision aid), no data are available regarding the manner and extent to which they were used.

Our findings that 50% of patients preferred screening post-decision aid and 28% completed screening (among patients with post-decision aid primary care encounters), contrasts with findings from what is, to our knowledge, the only other study to assess screening completion in individuals receiving a lung cancer screening decision aid. That study, conducted by Mazzone et al. in patients attending a tertiary screening program, found that 95% of participants completed screening after undergoing a shared decision making visit [20]. We hypothesize that the overwhelming majority of patients who attend a dedicated lung cancer screening program assume that the purpose of referral to such a program is to complete screening, rather than to decide about screening. When considering Mazzone’s findings alongside our results, it suggests that the time frame during which screening-eligible patients actually make decisions about screening is before they attend a dedicated screening program. Tertiary lung cancer screening programs are now being implemented in the US, and many claim to be able to conduct shared decision making. Our findings add to the discourse regarding the appropriate implementation context for medical decision making about lung cancer screening.

We found that the more knowledge participants had about benefits and harms of screening, the less likely they were to prefer screening. The fact that we did not observe differences in screening behavior suggests the need for additional research aimed at understanding how we can help ensure that patients receive care that is consistent with their preferences. This will likely require interventions beyond providing patient decision aids.

Our study examined decision aid effects on knowledge about two important harms of screening: overdiagnosis and false positives. We chose these outcomes because: 1) overdiagnosis and false positive tests can cause substantial harms in screened populations; 2) CMS explicitly requires that information about overdiagnosis and false positives be included in lung cancer screening decision aids; and 3) these harms may not be recognized or understood by patients making medical decisions about cancer screening [9, 15, 25]. Other knowledge domains are also probably relevant to decisions about lung cancer screening [8]. Further research is needed to assess the validity of measures of decision-relevant knowledge and to better understand knowledge thresholds at which patients may be considered adequately informed to make medical decisions about cancer screening.

We found relatively low concordance (58%) between (post-decision aid) preferences and LDCT ordering during subsequent provider visits. It appears that a major driver of discordance was that many patients who preferred screening and did not have an LDCT ordered did not actually have an opportunity to discuss screening with their provider. This finding points to an important problem in implementation of patient decision support in health care. Decision aids are intended not to replace but to inform discussions between patients and providers about medical decisions [30, 31]. However, competing demands and lack of adequate provider time to deliver preventive services are important barriers to effective communication and decision-making [16]. Further, lung cancer screening is especially complex given both the risk for lung cancer in this population and the chances of serious complications as a consequence of screening. Thus, further research is needed to understand how best to structure lung cancer screening decision support interventions in the primary care medical home to ensure that there is adequate time for patients and providers to discuss and deliberate. Moreover, more research is needed to understand the role that domains other than knowledge and stated preferences play in the complex picture of lung cancer screening behavior.

We found that, among primary care patients who are eligible for lung cancer screening based on USPSTF guidelines, viewing a lung cancer screening decision aid improved screening-related knowledge. It gave patients a more realistic perception of the likelihood of benefit. It also gave them a greater understanding of the nature of important screening-related harms. Our findings, although preliminary, suggest that a non-trivial proportion of screening-eligible patients may change their screening preferences after decision aid viewing. In contrast to findings in a referral population at a tertiary, sub-specialty screening program, screening preferences and behaviors among screening-eligible patients in a primary care population appear to be heterogeneous.