MEDICAL EDUCATION

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AVOIDING COMMON ERRORS IN KEY FEATURE PROBLEMS

Answers to Question 1
The most important differential diagnoses are the following:

1. Carcinoma lung (2 marks)
2. Chronic bronchitis or emphysema or chronic obstructive pulmonary disease (2 marks)
3. Gastro-oesophageal reflux (2 marks)
4. Unresolved infection, either atypical/undiagnosed agent including tuberculosis (TB), pertussis, viral and / or collapsed segment preventing resolution/post viral cough (2 marks)
5. Cardiac failure/ pulmonary oedema (1 mark)
6. Post nasal drip, chronic sinusitis/ rhinitis (1 mark)

Answers from the first four groups attract 2 marks each whereas the last two groups warrant only 1 mark each. You have to remember some answers are deemed more likely or important and hence are given more marks.

One of the commonest mistakes committed by earlier candidates is to write in more than the 5 diagnoses. Present candidates are wiser having been forewarned about the dire consequence of their over enthusiasm. However the pendulum has swung the other way around with candidates not daring to even attempt an answer for some cases thus failing their KFP. Others cannot get rid of their old habit and try to squeeze in 2 diagnoses on one line, with the hope that the examiner will pick the correct ones to mark. An example is provided.

1. Carcinoma lung /pulmonary tuberculosis
2. Chronic bronchitis / emphysema
3. Gastro-oesophageal reflux / asthma
4. Cardiac failure
5. Psychogenic cause

 

The candidate has actually offered 8 diagnoses, some of which are wrong. The scoring key provided to the examiner has the following caveats:

Number of responses requested = 5
Number of responses accepted = 5
Total score for this question = 9
Percent value for this question = 50%
No marks are to be awarded if candidate omits PTB as a possible diagnosis.

He is immediately marked zero because only 5 answers are accepted by the examiner.

Another candidate wrote the following:

1. Carcinoma lung
2. Chronic bronchitis
3. Gastro-oesophageal reflux
4. Cardiac failure
5. Smoker’s cough

He also gets zero marks because he has left out pulmonary tuberculosis (PTB)which is an important diagnosis to exclude because PTB is endemic in Malaysia. As a school bus driver, diagnosing this condition late will not only affect the patient’s lung function but poses a public health hazard of possible spread of the disease to the school children he is driving.

If your answer had been the following:

1. Carcinoma of lung
2. Chronic bronchitis
3. Chronic obstructive pulmonary disease
4. Pulmonary tuberculosis
5. Mycobacterial infection

You will be given only 6 marks because answers 2 and 3 are linked and 4 and 5 are from the same group of infection.

No marks will be given if you had listed Upper respiratory tract infection (URTI) and laryngitis as these are acute respiratory conditions. Mr Tan’s cough is unlikely to be due to asthma, post infective bronchial hypersensitivity or allergy as these would respond to bronchodilators. Dismissing Mr Tan as having Smoker’s cough is wrong because you must exclude important conditions like malignancy and PTB.

Answers to Question 2
The correct answers are Code 6 (2 marks), 11, 13, 14, 16 and 17 (all score 1 mark each). The examiner’s key for scoring (not given to candidates) is as follows:

Number of responses requested = 4
Number of responses accepted = 6 (Means 6 correct answers)
Total score for this question = 5
Percent value of this question = 50%

It appears that five answers can still be accepted for this question without any penalty although only four are requested. Unfortunately the candidate will not know about the examiner’s key for scoring. Hence to be on the safe side, STICK TO THE RULES and give the number of answers requested.

If you had read the question carefully, you will realize that the question asked for preliminary investigations (“organise first”). Note that Code 6, CXR, is given 2 marks because of its value in detecting lung conditions like infections (PTB) and Ca bronchus. In order to qualify for the full 5 marks, CXR has to be offered as one of the 4 options.

CT scan of the chest is not recommended as an initial investigation because it is not cost-effective. It can be ordered for staging of cancer or to clarify doubts suspected in the CXR.

Spirometry is awarded one mark because it can determine whether pulmonary obstruction or restriction exists and to quantify the amount if present. Unfortunately this answer is not usually offered by candidates in Malaysia because lung function test is not readily available here as a first line investigation unlike in Australia. Note that the Malaysian guideline has listed this as an essential item for the assessment of patients with chronic obstructive lung disorders. ³

The Malaysian guidelines on TB Management recognises that the Mantoux test has some role to play in the diagnosis of TB in children and extrapulmonary sites, 2 but in Australia, this answer does not attract any marks. The answers expected reflect the different practice in the two countries. TB is not an endemic disease in Australia unlike in Malaysia. Hence this test would not be offered for first line investigation.

In Malaysia, the Mantoux test is read after 72 hours. Interpreting a positive Mantoux test has to take into consideration several factors including endemicity and previous BCG vaccination. A diameter of less than 10 mm in induration indicates a “negative” result. However this does not exclude a diagnosis of TB. HIV patients with TB may give a negative Mantoux because their immunity is so suppressed that they cannot mount any reaction to the mycobacteria. A positive test indicates TB infection but this is not necessarily an active disease at the time of testing. A reading of 10 mm and above in a child or adult with no BCG vaccination is positive but a diameter of 15 mm is required for significance for a child who has received BCG. This strongly positive reaction also indicates a recent infection.

In conclusion, KFP is the most challenging aspect of the Part 1 Conjoint MAFP/FRACGP Examination. It is difficult but not impossible to surmount.  Most errors arise from failing to read the questions properly. Hence carefully reading the case scenario and adhering strictly to the instructions will minimise unnecessary loss of marks. You should also be familiar with all common family medicine problems, some of the rarer but important conditions like emergencies and current topics of interest like weight management, travel medicine, sleep disorders, bird flu, etc. 

REFERENCES

1. Hee HWJ. Handbook for Candidates, Mentors and Examiners. Conjoint MAFP/FRACGP Examination, 2007. Academy of Family Physicians of Malaysia.
2. Clinical Practice Guidelines for the Control & Management of Tuberculosis. 2006 The Malaysian Thoracic Society and Academy of Medicine. [Fulltext]
3. Zainuddin Md Zain (Chair). Guidelines for Management of COPD. Ministry of Health Malaysia, Academy of Medicine of Malaysai,  Malaysian Thoracic Society, 1998.