The Marking Rubric

In the appendix of the 2019A Examiners Report, the College published an example of the marking rubric that is used to mark the SAQs.

Question: Describe the metabolism and excretion of tramadol, including the implications for clinical practice.

Marking Domain23
Describes metabolic pathway for tramadolHepatic metabolism via cyp450 to active metaboliteAccurate – at least cyp2D6 to O-desmethyl tramadol (M1)
Describes excretion of tramadolRealises metabolites are renally excretedRenal excretion of metabolites but also some for active drug
Describes the genetic polymorphism associated with metabolismKnows of cyp2D6 polymorphism and describes at least one of poor or ultra rapid metaboliserAble to describe 4 basic groups of metabolisers at cyp2D6.
Realises implications of active metabolite for tramadolDescribes some implication but not well elucidatedMain opioid activity for tramadol provided by M1 metabolite ( up to 200x more potent at mu receptor than tramadol)
Poor metabolisers – limited opioid analgesia and converse for ultra rapid metabolisers.
Understands the clinical implications of tramadol metabolism in general for practiceMay suggest caution in renal impairment, but not accurate details of reason.Ultra-rapid metaboliser plus renal impairment – risk of respiratory depression.
Dose adjustment required in renal failure ( decreased dose or better to increase dosing interval to allow clearance of metabolite)
Answers both parts of the questionsMay answer one part well but misses the othermust
Internally consistent+/-yes

This is a kind of tabulated marking grid that has 2 salient features:

  • The marking grid is broken down into domains
    • These are points that you are expected to address in your answer, that can earn you marks
  • Each domain is scored out of 5
    • The more accurate and detailed your answer is in addressing the domain, the higher your score for that domain

This makes it evident that there are 2 important strategies to maximise your mark:

  • Identify the marking domains
    • This maximises your potential mark – if you address all domains, you could get full marks, if you only address half the domains, you can only get a maximum of 50% even if your answer is perfect
    • You need to recognise what is within the scope of the question and what is outside the scope of the question, so that you don’t waste your time writing stuff that can’t get you any marks
    • This is done by correct question interpretation
    • Whilst in more recent years, there has been an attempt to make the wording of questions as unambiguous as possible, and most questions are very straightforward, there are still questions that need to be interpreted with care
    • For example, 2022A12 Define cardiac preload, and describe its determinants
      • The first part of the question “define cardiac preload”, if taken strictly literally, would mean “write down a definition of preload” and that would be it
      • However, if we use game theory to analyse the question, what is the objective of the examiner in posing that question?
      • Is it to assess whether the candidate has memorised a definition for preload? No
      • The examiner’s objective is to assess whether the candidate understands what preload is
      • So you should interpret that part of the question to mean
        • What is preload?
        • How do we measure it?
        • What is its normal value?
        • What is its significance?
  • Maximise your mark for each domain by clearly demonstrating your understanding of the concepts
    • Major strategies
      • Clear explanations of the underlying mechanisms
      • Highlight significance/importance
    • Minor strategies
      • Support your point with an example or numerical data
      • Use keywords/buzzwords
      • Use precise language
      • Use diagrams

Clearly Demonstrating Your Understanding of a Concept

Clear explanations of underlying mechanisms

  • If you are explaining why poorly controlled diabetics might get polyuria, saying “hyperglycaemia → osmotic diuresis”, whilst not incorrect, would not get full marks because there are too many intermediate steps in the mechanism that have been skipped
  • A better answer might be “high plasma glucose → freely filtered in glomerulus → incomplete reabsorption in PCT (exceeds transport maximum) →↑ luminal osmotic load → prevent water and solute reabsorption in LoH → dissipate medullary concentration gradient → unable to concentrate urine → osmotic diuresis”
  • Use point form and lots of arrows
  • This goes a long way in showing that you understand something

Highlight significance/importance

  • Some questions explicitly ask you about the clinical significance or implications of a particular concept
  • Even if it does not explicitly ask this, you should do so as this shows better understanding

Support your point with an example or numerical data

  • You’ve just said that the closer the pKa of an LA to physiological pH → faster the speed of onset because of higher unionised fraction (lipid soluble) → can penetrate cell membrane to reach target site
  • Now support that point by providing evidence: lignocaine, pKa 7.9, unionised fraction 25%, has faster onset than ropivacaine, pKa 8.1, unionised fraction 15% (at pH 7.4)
  • Showing that you not only understand a concept, but can apply it demonstrates greater understanding

Use keywords/buzzwords

  • If you use the right key phrases in the right context, you can save yourself a lengthy explanation and still get full credit for understanding a concept, eg “Starling resistor” to describe West Zone 2 or CBF, “perfusion limited transfer” to describe transalveolar oxygen uptake
  • The more you use the words that the examiner is expecting to hear, ie the more your answer sounds like it came out of a textbook, the more it sounds like you know what you’re talking about

Use precise language

  • If you mean alveolar dead space, write “alveolar dead space”, not “dead space” and certainly not “V/Q mismatch”!
  • Being sloppy with terminology = this person doesn’t understand what those terms mean

Use relevant diagrams

  • Sometimes it is quicker to make your point graphically than to write it out
  • There is no point for duplicating information both in a graph and also in writing, eg if you label the P50 as being 27mmHg on your ODC graph, there is no extra mark in writing that fact again below the graph

Common Mistakes / Misconceptions

Misreading the question

  • It is surprisingly easy to misread a question under the pressure of the exam environment – you need to be aware of that and deliberately read each question carefully
  • It is easy to read over a question and think “ah, I’ve seen this repeat question before, great…” and miss that an important word has been changed
  • It may be helpful to underline key words in the question as you read it

Relying on a generic answer structure template rather than analysing what the question is actually asking

  • A common strategy is to start each answer with a section titled “Definitions” and define every key word in the question, then have a section titled “Introduction/Background” and write about the topic of the question generally, in the vain hope that this will get a few marks and possibly disguise a lack of knowledge – it will not, it will only waste time you could be using for another question
  • The examiners DO NOT want a nicely structured prose style essay answer, they just want you to put down information that answers the question asked
  • See this LA speed of onset model answer (scored 5/5) written by the examiner who wrote the marking rubric for the question. Notice that there are no definitions and no preamble/introduction – it just answers the question

Getting hung up on classifications/structure

  • Some people insist on trying to classify everything under nice neat headings, sometimes making up categories that, if anything, are more confusing than not having a classification
  • Sure, if a topic has a conventional classification, then use it – it will help make sure you don’t forget to cover something – but don’t feel that you need to force a classification onto everything
  • For example, questions like discuss the factors that affect duration of action of LAs, list the potential causes of inaccuracy for a pulse oximeter… I recommend just listing the factors and explaining each one

Strategies For the SAQ Paper

  • You are now allowed to write on the question paper during the 15 minute reading time. Use this time to plan out and write down the headings you will use in your answers – these should match the marking domains
  • You ABSOLUTELY MUST stick to the 10 minute time limit per question. If you haven’t finished writing your answer at the end of 10 minutes, move on to the next question. If you have spare time at the end, come back to finish off your answer then