The results of this study show that patients infrequently file a written complaint related to a radiological procedure that they have undergone at a tertiary care institution in Europe, with an overall complaint frequency of 14.4 per 100,000 radiological procedures. Moreover, the complaint frequency did not increase over time. In addition, nearly half of all complaints were of low severity. Although these results appear reassuring, it is imperative to keep the number of patient complaints to a minimum in light of the concept of patient-centered radiology and the growing trend towards more detailed public reporting of patient satisfaction data with benchmarking and links to financial reimbursements .
Interestingly, the majority of complaints were from outpatients and were shared complaints. The former cannot be explained, but the latter is plausible given the role of radiology as a supporting specialty. It is also interesting that the departments of surgery and orthopedics were most frequently involved, both as the primary treating specialty and as co-recipient of the complaint. This is in line with the results of a study by Tibble et al  that reported the rate of patient complaints to be 2.3 times higher for surgeons than for other (non-surgical) physicians. In addition, male surgeons were reportedly at a higher risk of complaints, as were specialists in orthopedics, plastic surgery, and neurosurgery . Tibble et al  speculated that this elevated risk arises partly from involvement in surgical procedures and treatments, but also reflects wider concerns about interpersonal skills, professional ethics, and substance use.
Among all radiological procedures, interventional radiology was by far most susceptible to patient complaints. This is probably related to the more invasive nature of interventional radiology, with associated risk of complications and side effects. Another issue is that patient-physician communication may sometimes be compromised because of the higher time and work pressure for interventional radiologists who frequently deal with urgent and/or technically complicated procedures [3, 11]. In addition, it should be noted that in our institution, pre-intervention radiologist-patient consultations are only held for elective neuro-interventional procedures. Furthermore, the waiting time for some elective interventional radiology procedures (which could be up to several months) was also a common trigger for complaints in the present study.
Patients also filed significantly more complaints related to cross-sectional imaging (CT, MRI, and ultrasonography) than to conventional radiography. In general, planning, acquisition, and interpretation of cross-sectional imaging modalities are more complex and time-consuming than conventional radiography, and therefore more prone to adverse incidents and errors that may be perceived by the patient as below standard care. It can also be speculated that patients who undergo cross-sectional imaging generally have an a priori worse condition and more frequently have a more serious underlying disease. Furthermore, a study by Ollivier et al  showed that the vast majority of patients (73%) experienced their CT and MRI scans as distressing, both due to the scan procedure itself and due to fear of the results. These patient and scan-related factors may potentially lower the threshold for patients to complain.
According to patient complaint taxonomy , most complaints were related to the clinical domain, followed by the management and relationships domains. Quality, safety, timing and access, and communication comprised the far majority of complaint categories, and these targets should be prioritized with respect to both staff education and incorporation into continuous improvement systems (quality circles, total quality management, plan do act, Kaizen, etc.) . Written patient complaints provide a valuable input for such continuous improvement systems. On the other hand, actively assessing patient (dis)satisfaction in the radiology department by means of routine patient surveys may perhaps be more desirable, because it provides a much broader and systematic view of how patient-centered radiology is delivered and may actually prevent patient complaints. However, except for the Press Ganey patient satisfaction survey for radiography and US performed in the outpatient setting , standardized and validated survey instruments for other imaging modalities and clinical settings are currently lacking.
Only one previous study, by Salazar et al , evaluated radiology-related patient complaints. This study was performed at Massachusetts General Hospital and comprised the period 1999–2010, in which 153 complaints were filed . Their complaint frequency per 100,000 procedures was lower (2.38) than ours (14.4), but a common finding was the significantly higher incidence of complaints associated with interventional radiology procedures . Most of their complaints (60.1%) could be grouped under the denominator “failure to provide patient-centered care,” but direct comparison with the present study is difficult because Salazar et al  did not use the standardized coding taxonomy developed by Reader et al . Furthermore, their results may not be applicable to hospitals outside the USA due to differences in healthcare provision indicators and socio-economic patient variables , as mentioned before.
This study had some limitations. First, it was performed in a tertiary care university medical center in Europe, and the results may be different in non-European and non-academic hospitals with other patient populations. More personalized contacts between radiologists and patients may decrease complaint frequency , but this requires further investigation. Second, only unsolicited patient complaint letters were available for analysis. Many unhappy patients may not formalize their complaints, while they would express dissatisfaction in a survey or in any other easier way of addressing discontent. In addition, although the institutional protocol dictates that all written patient complaints received by individual clinicians should be sent to the independent complaints officer, it was not possible to check if this protocol was always followed. Therefore, the true extent of patient dissatisfaction may have been underestimated. Furthermore, those who actually decide to file a written complaint may not be a representative of the whole spectrum of patients, since they may constitute the most vindictive part of them. Spending energy to address their complaints may only solve a limited part of the entire patient dissatisfaction issue.
Third, although a response letter was sent to all patients on behalf of the head of the department, explaining and (if applicable) apologizing for the situation, there was a lack of patient feedback and information on whether the complaints were resolved.
In conclusion, written patient complaints directed to a department of radiology at a European tertiary care center are relatively few in number and have not shown a temporal increase. Knowledge of sources of patient dissatisfaction may help to reduce the number of patient complaints and improve patient care.