Choice of health care provider is often dictated by location. People who move over large distances have to switch provider. In addition health care systems have increasingly seen the introduction of market mechanisms (1,2) in which switching of providers is encouraged (3) as a means of improving competition. Contact with a new patient is an opportunity to offer treatment and so a potentially undesirable medical side effects of patient switching is excessive treatment. It is well-established that some types of provider remuneration such as fee-for-service (4), increase the propensity to treat leading for calls for it to be replaced or regulated. Where a treatment is potentially harmful this implies that there might be a risk to a patient who is either forced to or chooses to switch provider. To this end, we examine whether patients are exposed to additional ionizing radiation upon switching between dentists under different provider payment schemes. We exploit large-volume individual-level administrative data and the unique characteristics of the most frequently applied type of medical imaging: dental X-rays. We focus on variations in the use of dental radiographs when patients switch between providers who receive either fee-for-service or salary payments.
Medical radiography is associated with a radiation risk for patients. While X-rays serve a crucial role in diagnostics, radiation exposure is a well-known human carcinogen (5). Dental X-rays are among the most used medical radiographs and the most common source of artificial radiation exposure (6). Current clinical guidelines in many countries confirm that dental radiographs should only be used if the patient’s benefits exceed the risks, that is only upon strict clinical indication (7). Nonetheless the procedure is frequently delivered as part of a routine examination, especially when visiting a dentist for the first time. There is little evidence on the exact carcinogenic effects of low dose radiation, such as caused by dental radiographs, because the sample sizes required to study them would need to be extremely large (8). The consensus held by radiological protection organizations is based on the so-called linear no threshold (LNT) model, which postulates that risk of radiation induced cancer increases linearly with exposure and that there is no safe threshold (9). Indeed, a number of studies have been able to show an association between dental X-rays and the risk for meningiomas and salivary tumours (6,10,11).
It has been established that health care providers adapt their behaviour to financial incentives (12). Ideally, financial rewards can be used to improve providers' performance and the quality of services provided (13). Empirical evidence however remains weak that these goals are easily achieved (14,15). Previous studies have found that the introduction of financial incentives has increased treatment intensity and created supplier induced demand. Evidence indicates that this often constitutes ineffective care with little effects on patient health, rather than a reduction of existing rationing (16).
Most of the existing literature on the topic has focused on general medicine, however there is a growing body of evidence looking at dental care in particular (17,18). Studies show that financial incentives have the potential to increase utilization of dental check-ups (19) and increase the number of individuals under dentist supervision without a reduction in service quality (20). However remuneration schemes used for dentists can enable the provision of additional care with limited or no marginal benefits for patients (21) with potential adverse effects for patients (22). Notably, fee-for-service payments have been shown to increase the probability of dental radiographs being provided to patients (23). Ours is the first study to focus on the impact of switching dentist on this potentially harmful treatment.
Based on existing studies of the impact of fee-for-service arrangements in general and for dentistry in particular, our hypotheses were that (i) patients receive significantly more dental radiographs upon switching to another dentist; and (ii) the effect on dental radiographs upon switching to another dentist is significantly larger under fee-for-service as compared to salary payment.