The variability of patient preferences

Abstract

Background: Wide variation in procedure utilization suggests that surgical indications might not be rigorously defined. An alternative explanation is that surgical outcomes are valued differently across groups. When a patient, using the information provided by the surgeon, places high value on successful results or is indifferent to the costs of ineffective treatment, the treatment threshold is lower and more surgery will be chosen.

Questions/purposes: Is there a high variation in patients' preferences and, therefore, high variation in treatment thresholds? Do people poorly estimate their own treatment thresholds?

Methods: I presented a hypothetical scenario describing a diagnostically uncertain meniscus injury to 100 college students, asking them to rate the value of the four end points based on treatment choice (arthroscopy chosen/declined) and post hoc knowledge of the true diagnosis (tear present/absent). From those data, I calculated treatment thresholds. Subjects also estimated their treatment threshold directly.

Results: The calculated treatment thresholds ranged from 4% to 88%. A discrepancy of at least 20% between the calculated and subject-estimated thresholds was present in 61 subjects.

Conclusions: There is great variance in the treatment threshold reported; additionally, many subjects poorly predicted their own calculated treatment thresholds.

Clinical relevance: Variability in patient preferences for outcome is an important, but perhaps underestimated, clinical parameter. Meaningful assessment of patient preferences when recommending treatment or creating clinical practice guidelines will lead to better shared decision making.

Fig. 1

The decision tree shows the options offered to the subject and the possible outcome states. The four terminal nodes are as follows: arthroscopy was chosen and a tear was present (denoted as Rx+ Dx+); arthroscopy was chosen and no tear was present (denoted as Rx+ Dx); nonoperative treatment was chosen but there was a tear (denoted as Rx− Dx+); and nonoperative treatment was chosen and there was no tear (denoted as Rx− Dx−).

Fig. 2

A histogram shows distribution of derived (calculated) treatment thresholds. Most subjects had a treatment threshold near 50%. However, the responses ranged from 4% to 88%.

Fig. 3

A sample guideline shows management of a possibly infected knee arthroplasty. (Modified from Figure 6 and published with permission from Leone JM, Hanssen AD. Management of infection at the site of a total knee arthroplasty. J Bone Joint Surg Am. 2005;87:2336–2348.)

Fig. 4

A modification of the guideline shows consideration for patient preferences. Patients who highly discount future gains or who place high cost on the possibility of a second surgery (broadly grouped as type Y patients) should have immediate revision surgery. Patients with low discount rates or who ascribe relatively low costs to the possibility of debridement failure should retain their prosthesis if it is well fixed and try a course of antibiotics. (Modified from Figure 6 and published with permission from Leone JM, Hanssen AD. Management of infection at the site of a total knee arthroplasty. J Bone Joint Surg Am. 2005;87:2336–2348.)