What is a Key Feature?

As a GP when a patient comes in with a problem we usually start with a blank sheet and by the end of the consultation come up with a problem list and management plan. For example a patient with abdominal pain, our list of differential diagnoses is huge. It ranges from the serious: cancers, surgical emergencies, pregnancy emergencies; to the less severe: dietary intolerances, anxiety, viruses – and any number of things in between. As the doctor you narrow down that list of differentials by using your history, examination and investigations. The thought process going through your mind as you move from one question to the next based on the clues the patient gives you is called clinical reasoning and it is largely hidden from the patient. This process of clinical reasoning is the skill that the Key Feature Problem (KFP) test examines.

The cues that move you closer to one particular differential diagnoses or guide one particular management plan have been learnt by you over many years of study and practice. These are clues in history, examination or results. These clues are unique to your patient and their situation, we call these Key Features. In the KFP exam you are provided with many key features in the stem and you need to identify these to help you answer the questions correctly.

Imagine a patient comes to see you:

57 year old male comes to you with lower tummy pain that has been bothering him for several weeks, particularly at the end of a long day. He works as a carpenter and noticed the pain after a particularly arduous day trying to finish a job before the COVID19 lockdown. He is feeling stressed about his situation, especially financially, and has put off seeing you because of this. The pain is constant but worsens if he lifts something or bends down, it seems to improve when he lies down. One night last week he felt the pain did not improve with lying, he felt nauseated and felt a hard lump near his groin. After a few hours the pain gradually eased, then he felt it was time to come and get it checked out. There are no other medical records in your file, he tells you he drinks up to 8 standard drinks a day and does not smoke.

 We might think this man has an inguinal hernia that is at risk of incarceration. What helped you guess? Let’s look at the key features:

  • Demographics: 57yo male, working as a carpenter put him in the right risk group.
  • Presenting complaint – lower tummy pain, came on after an arduous day, worse with lifting/bending.
  • Associated symptoms – episode of severe pain that lasted longer than usual, nausea, hard lump near his groin
  • Past medical history – nothing notable
  • Other information – stressed, financial concerns, put off seeing doctor due to this, drinking heavily

These Key Features will guide you to your next steps – how might you examine him? What investigations would be appropriate? What about referrals? What advice do you need to give him as a safety net given his episode of severe pain? Do you need to consider the financial impact of your recommendations? Did you pick up the clues about being stressed, affected by COVID-19 and drinking heavily? What kind of follow up to you need to do there?

This is how you are working with patients every day, the KFP exam is only putting it into writing. In order to help you prepare for the exam, consider doing some random case analysis on patient’s from your day. Write down the key features from their presentation. Then think about how the case turned out – were there any key features you missed? Would you do anything differently? Maybe discussing it with a colleague or supervisor would shed more light on the case. You can do this with Telehealth patients too, where picking up small details in history can be even more important.