Table 1.

“Intrapersonal factors” affecting clinician test ordering behaviour, with number of articles and quotes from articles

Factor	Articles	Illustrative quotes
Fear of malpractice and litigation	34 articles [1, 2, 7, 21, 23, 31–39, 42, 45–47, 49, 59, 60, 62–64, 68–77]	“You are so open for being sued by anything but it’s very easy to want to lean towards the screening everyone … I definitely think it’s hard not to think legally” [45] “Once the issue has been raised, it is difficult to back away unless you are 100% because you are responsible if you are wrong” [45] “I’m often a bit defensive...I guess that’s partly that legal thing” [45] “I think the whole medical-legal thing also makes people more inclined to CT [computed tomography] someone even if they have a pretty low suspicion just ‘cause no one wants to be sued” [47] “I think litigation is a problem; you miss one neck... fracture or bleed in the brain you are going to court” [62]
Clinician knowledge and understanding	25 articles [2, 3, 5, 21, 37, 40, 41, 43, 45–47, 49, 50, 58, 62, 64–66, 72, 73, 78–82]	“How much work [laboratory testing] is, how much it costs, how much normal results can fluctuate, things like that, I think we know very little about that” [3] “Nothing can really go wrong [with overutilization]” [3] “You understand the natural course of disease and the point in time at which you have to make a decision to do something different” [37] “When I’m admitting a patient or doing clinical work, it’s kind of affected my thought process to where I think a little bit more about ‘do I really need to get this test?’, ‘will it really change management?’, ‘could it potentially be harmful to the patient?’” [40] “Those like statistical issues don’t apply to the individual...because...they make their decisions on a set of complex, but perhaps irrational basis, you know, anxiety and...” [45] “Yeah, so, I hate the D-dimer. I understand its utility. I think that too many D-dimers are sent... I think the decision to get a CTPA [computed tomography pulmonary angiogram] should be based on a clinician’s clinical reasoning plus or minus the criteria, plus or minus a D-dimer” [47] “As I said, a patient without previous medical history, without symptoms. In this case, I have never auscultated a lung and thought: “Thank god I listened to that lung.” I mean, what do you expect from a healthy patient when you auscultate the lung? A healthy lung” [49] “GPs may be playing a good game and saying I’m not going to bother this patient with having a GFR [glomerular filtration rate] of 59 because I know that although it qualifies as CKD [chronic kidney disease] 3 it’s not gonna make any difference to how I manage that patient and I think that’s good medicine” [50] “When you have no idea what’s going on, so it gives you something to hide behind” [62] “‘Should be tailored according to family history, previous issues, lifestyle and previous findings. Need to explain the limitation of check-ups” [65]
Intolerance of uncertainty and risk aversion	24 articles [1–3, 7, 21, 23, 32, 33, 35, 37, 39, 42–44, 46, 47, 49, 53, 64, 69–71, 73, 83]	“Lab testing is often only done for the doctor’s peace of mind.” [3] “I am worried if they don’t have a full assessment and I miss something that it is going on with their heart that is not apparent because ECGs [electrocardiograms] and clinical examinations are not very precise” [37] “What if it couldn’t wait? How would you know it won’t affect them?” [45] “You’re sitting there with someone who has a sudden-onset splitting headache, but otherwise you see nothing alarming … A CT scan for an acute headache. Even if the pre-test chance is 0.01. He does it anyhow. They have much more certainty than we do.” [46] “You have to be self-confident in not doing something” [49]
Cognitive biases and experiences	12 articles [15, 21, 36–38, 45–48, 60, 84, 85]	“‘There might be a bias to a situation where some doctors missed an important finding, when they were a junior doctor, so they always do scans because they are worried that something might happen like years ago” [37] “It’s certainly a—hard to be, treating dying people who are young and not to worry about all of this and I, but I try not to change my practice based on my own personal experience of one or two people dying of prostate cancer” [45] “If you’ve ever experienced something like that, you can be sure that you’ll send patients with vague complaints for further testing much faster. Absolutely” [46] “I would say that my clinical experience highly in- fluences my ordering … sometimes I feel a certain way about a patient even though they don’t fit a certain profile and I’ll end up doing something additional for them” [47] “The initial thing was PSA [prostate specific antigen] is useful and that has basically stuck in my head, that PSA testing is useful” [60]
Sense of medical obligation	6 articles [16, 45–47, 49, 50]	“To not screen somebody, I don’t know, it seems cruel, it’s cruel and irresponsible... to not at least make an attempt to avoid the misery of a person getting prostate cancer, to me, seems unbelievably cruel” [45] “We have to diagnose them if they have a problem” [45] “Some GPs mentioned their frustration at not being able to offer the patient something useful, at the feeling of empty hands, owing to the lack of a diagnostic or therapeutic plan for patients presenting with unexplained complaints. A test request symbolises a serious attempt to deal with the patient’s complaint” [46] “If it’s on your radar … you’re almost honor-bound to do the study of choice” [47] “‘Action’ dogma of doing anything possible for the individual patient” [49] “My personal policy I would always disclose...generally speaking I would always explain the diagnosis” [50]