Measuring decision quality: psychometric evaluation of a new instrument for breast cancer chemotherapy

Abstract

BackgroundWomen diagnosed with early stage (I or II) breast cancer face a highly challenging decision – whether or not to undergo adjuvant chemotherapy. We developed a decision quality instrument for chemotherapy for early stage breast cancer and sought to evaluate its performance.MethodsCross-sectional, mailed survey of recent breast cancer survivors, providers, and healthy controls and a retest survey of survivors. The decision quality instrument includes questions on knowledge and personal goals. It results in a knowledge score and concordance score, which reflects the percentage of patients who received treatments that match their goals. Hypotheses related to acceptability, feasibility, validity, and reliability of the survey instrument were examined.ResultsResponses were received from 352 patients, 89 providers and 35 healthy controls. The decision quality instrument was feasible to implement with few missing data. The knowledge scores had good retest reliability (intraclass correlation coefficient (ICC) =0.75). Knowledge scores discriminated between providers and patients (mean difference 31.1%, 95% CI 26.9, 35.3) and between patients and healthy controls (mean difference 11.2, 95% CI 5.4, 17.1). Most providers reported that the knowledge items covered essential content. Two of the five goal items had a ceiling effect, and one goal had low content validity. The goal items had moderate retest reliability (ICC’s 0.57 to 0.78). In the multivariable model of treatment, none of the patient goals was associated with receipt of chemotherapy. Age and hormone receptor status were the only variables independently associated with chemotherapy. Most patients (77.6%) had treatment concordant with that predicted by the model. Patients who had concordant treatment had similar levels of confidence and regret as those who did not.ConclusionsThe Decision Quality Instrument is a reliable and valid measure of patient knowledge about chemotherapy, but its ability to measure concordance with patient goals is limited. In this sample, patient goals were not associated with treatment, and most patients reported they were not asked their preference, suggesting that goals were not adequately considered in decision making.

How Informed Is the Decision About Breast Reconstruction After Mastectomy?

“…14–16 Patients also have incomplete knowledge about systemic therapy, with frequent overestimation of the survival benefit of chemotherapy. 17, 18 Our participants were more educated than the average population of women undergoing mastectomy for breast cancer, and could all read or speak English. Given the demographics of our study population, we expect that knowledge about reconstruction in the breast cancer population at large may be even lower than what we found here.…”

“…10 Further details of the DQI development and validation process have been described before. 10–12 The DQI covers three broad domains.…”

Association between perceived benefits and receipt of radiotherapy among older breast cancer patients

“…Previous studies examining knowledge retention and decision making among patients with breast cancer have concentrated on surgery (mastectomy vs breast‐conserving surgery) or systematic treatments . The results indicated that patients with breast cancer often overestimate treatment benefits .…”

“…[9][10][11] The results indicated that patients with breast cancer often overestimate treatment benefits. 9,10 For instance, less than one-third of women with breast cancer correctly reported expected mortality from breast cancer without chemotherapy or hormonal therapy; most patients who answered incorrectly overestimated the benefit of chemotherapy. 9 Similarly, only slightly more than half of patients correctly reported no survival difference between breastconserving surgery vs mastectomy within 24 hours of surgical consultation.…”

“…Previous studies examining knowledge retention and decision making among patients with breast cancer have concentrated on surgery (mastectomy vs breast‐conserving surgery) or systematic treatments . The results indicated that patients with breast cancer often overestimate treatment benefits . For instance, less than one‐third of women with breast cancer correctly reported expected mortality from breast cancer without chemotherapy or hormonal therapy; most patients who answered incorrectly overestimated the benefit of chemotherapy .…”