Based on the literature, our clinical experience, and discussions with colleagues, we have developed a conceptual model of CKD referral decisions for older adults experienced by the PCP (Fig. ). This model is similar to previous descriptions of decision models developed from illness script theory.52
Illness script theory developed as a means of understanding the complexity of physician diagnosis and management of patient illnesses. In illness script theory, there are 2 main domains: (1) enabling conditions that include medical and nonmedical patient factors that influence the probability of disease and (2) consequences that include signs and symptoms of the illness thought to influence the diagnosis of disease. In modeling referral behavior, van Schaik et al.53
added physician characteristics as another important contributor to the decision outcome. Our model similarly describes patient characteristics, including enabling conditions and consequences, and physician characteristics that interact to influence a referral decision.
Figure 1 Conceptual model of referral decision making for chronic kidney disease. Arrows represent hypothetical direction of influence. References are for factors previously evaluated in either general referral decisions or in decisions about initiation of dialysis. (more ...)
We make some simplifying assumptions in this model: (1) The patient is asymptomatic from the condition of concern, as is generally the case in moderate to severe CKD, (2) the patient has no strong preferences with regard to the decision to refer them to a nephrologist (i.e., they will follow the PCPs recommendation), and (3) the physician’s sole motivation is the best care for the patient.
The conceptual model presented in this study (Fig. ) identifies the referral decision faced by the PCP for an individual patient encounter. At this encounter, the PCP can decide to either make a referral of the CKD patient to the nephrologist or to continue to follow the patient in clinic. If the physician chooses to refer the patient, then the decision allows for exit from the model. If the physician chooses to follow the patient then 1 of 3 clinical scenarios may occur, the CKD may improve, stabilize or worsen. Any of these scenarios may be readdressed at the next clinical encounter; therefore, the referral decision may be a recurrent decision, and the decision tree is not different between early and late referral, although the variables associated with that decision may differ or be weighted differently. Also, it may be that the referral decision is a “silent decision,” meaning the physician decides without the input of the patient, which may occur if the physician feels that the harm from the explanation to the patient outweighs any clinical benefit at that particular encounter.54
The patient characteristics that are thought to influence the physician’s referral decision include not only enabling and consequence factors as described in the illness script theory but also demographic factors previously shown to influence either general referral decisions or decisions about dialysis initiation, ‘geriatric-appropriate’ factors like cognitive and functional status, and patient preferences. For example, a patient with moderate–severe dementia who requires assistance with all instrumental activities of daily living and 2 activities of daily living might be less likely to be referred than a person of the same age who lives independently. While we acknowledge that the patient’s preferences are important, it is more likely that the decision to refer the patient to a nephrologist will be made by the physician after taking into account patient factors (including preferences), especially given that patients often do not know their renal function and are less likely to have well-formed preferences regarding treatment issues upstream from dialysis.55,56
We also have included physician-specific factors that also might influence referral decisions including experience, demographics, and disease-specific knowledge previously thought to play a role in physician decision making, as well as physician management of clinical uncertainty and expectations of specialists. Finally, the effect of patient variables on physicians may be modified or mediated by the relationship between the patient and the physician. Most of these factors have yet to be explored for CKD, including the duration of the patient–physician relationship, the patient’s level of trust in the referring physician, and health behaviors.
Because of the nature of CKD in which physicians have significantly more information about the stage and consequence of the disease than patients (especially given the lack of public awareness about renal disease and lack of symptoms until very advanced disease), other better known models of decision making are less applicable.3
For example, the health belief model is patient-centered and focuses on patient-perceived health and preventive behaviors, whereas the transtheoretical model of change generally focuses on patient behavior changes.57,58
Neither model applies to CKD referral choices by PCPs. Despite the emphasis on shared decision making in the broader literature on the patient–physician encounter, fewer than 10% of therapeutic decisions are arrived at with clear inclusion of patients, and in most cases, patients behave passively.59,60
Little is known about shared decision making in the referral decision, although 1 study indicates that there is increased participatory decision-making for patients when referrals are made; however, the level of this participation has not been quantified.61