• Explain the basic of objective structured clinical examination (OSCE).
• Write OSCE stations for different practical setting.
• Conduct an OSCE in actual clinical setting.
• Evaluate a case presentation objectively.

One of the most important aspects of training of a doctor is acquisition of practical skills - after all, patients so not come to quiz their doctor on the differential diagnosis or management of their problem. Yet, objective assessment of practical (or psychomotor, as they are called) skills poses a formidable challenge for an examiner, Have you ever wondered during a practical examination regarding points to discriminate between good and not - so - good students ? Often, the evaluation is so subjective that different examiners grade the students on their own criteria. For a minute, recall one of the basic purposes of evaluation - yes, you are right- providing feedback to the student. Unfortunately, our conventional examinations do not provide any feedback except saying pass or fail and thus do not provide any opportunity to the student to improve.

There have been many innovations to overcome this problem but the one that we are going to discuss with you is called OSCE. Sounds like a French name ? Well, OSCE stands for Objective Structured Clinical Examination and has been designed for objective assessment of bed side clinical competence. Let you may have doubts about this mode of examination, let us weigh OSCE in the desirable qualities of an assessment   instrument viz. validity, reliability and feasibility.

Validity, you will recall is the ability to measure, what is intended be measured. A practical examination should evaluate the ability of a candidate to obtain relevant history, perform a physical examination, reach a probable diagnosis, interpret laboratory reports and recommend a management protocol. As we shall discuss with you a little later, all these can be assessed by OSCE. The conventional examination, on the other hand focusses on reporting of abnormal findings only, ignoring the 'doing' part of it.

Reliability as you have learnt, refers to consistency of measurement. In an OSCE, all students examine the same patient and are marked on predetermined 'checklists' with the results that inter- observer variation is reduced to a minimum. Thus, any difference in marks is more directly attributable to the ability of the students, rather than to extraneous factors.

By now you must be wondering about what exactly OSCE is, Let us now describe it for you. As the name indicates, it is a farm of practical examination which is objective and which owes its objectivity to a structured marking scheme. Let us elaborate further. Suppose a patient has an enlarged liver, 4 cms below the costal margin. In a conventional examination, the student will tell the examiner 'liver is 4 cms' and get credit for it - although he may have palpated it standing on the left side of the patient ! On the other hand, if he is given a mark for each of the following points - makes the patient comfortable, warms hands, stands on the right side of the patient, palpates gently and so on, - then the assessment is likely to be not only objective but also more valid.

Each task assigned to the student is called a station. Thus, depending on the situation, a number of stations are set up and students rotate on them, spending a specified time on each one of them (usually between 3-5 min). It means that the task presented at each a longer time is required, then, the task should be subdivided into 2 stations. (eg. Superficial reflexes are elicited on one station while DTR on next.)

Don't be afraid of designing the stations - they are easy to design if you understand the basics of it. Generally stations are of two types - procedure station and question station. As the name implies, at procedure station can be further subdivided into observed and unobserved. An example of each of these type of stations will make the difference clear.

Unobserved procedure station :
Record the weight of the infant

Check list for examiner :

You have rightly noted that on observed procedure station, the student is being observed by an observer on the basis of a check lists are the 'heart' of OSCE. To prepare a check list, you have to list all the acts that go into, a differential weightage is assigned to each of the acts. Thus, in the above example, if checking the zero - level is considered to be more important than the others, then it is given 2 marks while the rest of the points are given 1 each so that a student who performs all the acts correctly is given 6 marks for this station.

It is obvious from the above that any range of competencies can be tested by OSCE. Competencies like history taking, physical examination or bed side lab procedures require an observed procedure station while interpretation of lab reports, x-rays, ECGs, pictures etc. can be done by unobserved procedure stations.

Question station :
Regarding the case that you have just examined, write True or False.

Procedure Station

Question Station :

In the x - ray you have just seen -

Both these examples would have made it clear that OSCE prompts the student to perform the complete procedure at one go - if he has not palpated axillary nodes or looked for evidence of rickets, he cannot go back to review his findings.

Coming to the actual planning of OSCE, it is better to decide before hand the competencies to be tested and weightage to be given to each. Look at the following example :

In effect, it could mean that there will be 3 stations on history taking (of 10 marks each), 3 on physical examination and so on. Let us make it clear that these are only recommendations and depending on individual requirements, a variation can be made. Thus, for junior students, more emphasis may be laid on history taking and physical examination while interpretation can be given more emphasis in later years. Once this decision has been made, the whole examination will look like a circuit of stations, though which all students rotate. For a 20 stations OSCE, the total time required, assuming a time of 5 min per station, will be approximately 2 hours. You will agree that objectively examining 50 students in 2 hours will never be possible by a conventional examination.

• History talking : The student takes history at an observed or unobserved station. At observed station, he is marked by an examiner while unobserved stations are followed by a question station.
• Physical examination : The student is asked to perform physical examination and is marked on a check - list. Competencies ranging from a simple inspection (for spot diagnosis) to neurological examination can be tested in this way. If the desired physical examination is likely to take more than 3 - 4 mins, then the station should be split into two. For example, at one station the  students tests for sensations while at the next, he elicits the tendon reflexes.
• Charts and photographs : For example, a strip of ECG, or reports of blood gas analysis or photographs of congenital defects can be exhibited to represent cases which may be difficult to get at examination time.
• Laboratory data interpretation. Hematology, biochemistry and radiology reports can be objectively tested.
• Communication Skills : The student can be asked to explain to the patient the dose of drugs, or diet to the mother of a malnourished child or importance of immunisation and so on. By use of appropriate check lists, these skills can be objectively evaluated in a very short time.
• Instruments : The indications for  use and handling of common instruments can be evaluated.
• Beside lab tests : Actual procedure of urine, stool, blood examination etc.
• Practical procedures like giving an injection or passing a nasogastric tube using models.
• We have given here a few more OSCE stations as illustrations. You can also make your own stations , using them as guidelines.

Check - list for Examiner :

(This station is for assessment of communication skills and attitudes of the student.)

Observed Procedure Station : Determine the immunisation status of the child.

Check - list examiner : Enquires specifically regarding following vaccinations

A 3 year old child has the following anthropometric measurements.

Use the percentile charts and write True or False for the following statements :

Unobserved Procedure Station Perform the abdominal examination of this child.

Question Question - Write true or false regarding the child you have just examined.

2.In situations where the examination may be uncomfortable, multiple alternative cases may be used for the station depending on the number of students. But you should be careful that the question station pertains to the particular case used.

Check - list for examiner

From the above, it would have become clear to you that OSCE makes practical examination not only more valid but also more reliable. It can be used for a large number of students in a relatively lesser time. Moreover, by analysing the check - lists, feedback can be provided to teachers as well as the students regarding efficiency of teaching. For example, if in the palpation of liver station, it is found that most of the students are not percussing the upper border of liver, then in subsequent teachings, this point can be made more explicit.

It is not that OSCE does not have its critics - and the major criticism is that it tends to segregate the patient's problems into components rather than testing him as a whole. This may be true to some extent but most often, it is the design of stations that is at fault rather than the examination itself. This drawback can also be overcome by combining OSCE with a traditional clinical case presentation.

Clinical case presentation is liable to be influenced by a number of factors including language, dress , sex , poise and confidence of the student. Also, often more time happens to be given to the students at the begining of the examination as compared to the latter part of it.

Could clinical case presentation be modified to make it less subjective ? It is difficult to conceive a great deal of objectivity within the traditional system, but attempts can certainly be made. One method would be to make a check list of important desired points in history and examination including accuracy of clinical findings. The desired weightage for each component would of course have to be predetermined. Certainly it would be an exhaustive exercise and needs a through study of the case prior to the actual evaluation. While some senior and experienced examiners may frown at the idea, the fact remains that many examinations follow a haphazard pattern like sailing an uncharted sea. Would it not be fair to the student that evaluation is systematic and organised ? Look at the guidelines given below , being followed by University of Limburg. You will appreciate that by using such a check list, the objectivity of case presentation can be significantly improved.

Objective Structured Case Record

History taking :
Pace / Clarity
Communication Process
Systematic presentation
Correct facts established

Physical examination :
Systematic
Techniques
Correct findings established

Management :
Appropriate investigations
Logical sequence
Appropriate management

Clinical Acumen :
Problem identification
Problem solving

Any Other Points

If  we put it little more bluntly, it can be said that whether it is evaluation of clinical skills or evaluation of clinical acumen, the onus of being objective rests on you. If you are clear and consistent on how you are going to mark. You will be fair to the students and also help them in learning better. Remember the age old dictum that justice should not only be done but it should also appear to be done. It is only by using these kind of tools that you can rebuild the faith in the examination system.

Before we conclude this discussion, let us remind you that any innovation in education requires time and effort. The time involved in setting an OSCE is definitely more than that required for a traditional examination - however, the increased reliability more than compensates for it. Further, once a bank of OSCE stations is built up, subsequent examinations become much easier to conduct and take considerably less time.