Question

Q4. Consider the following from Lokken and Skjelbred (1980). B J Clin Pharm 10(S2):

Research question: Can paracetamol reduce the inflammatory response to surgical removal of a

non- erupted third molar?

Population: people with impacted wisdom teeth.

Samples: 16 females, 8 males otherwise healthy, with non-erupted 3rd molars (one on each side)

that needed surgical extraction. Age range 19 – 34 years.

Design: Double blind cross-over (within-subjects) study to compare paracetamol with placebo.

Subjects had surgery for one tooth, followed by surgery for the second tooth 28 days later.

Method: Tooth extractions were performed by the same surgical team, on Tuesdays between 9 –

11 am. Twelve patients received the active tablets at the first operation (1g paracetamol, 4x daily

for 2 days), then inactive tablets for the second operation. The remaining 12 patients received

inactive tablets for the first operation, and active tablets (same dose regime as first half of subjects)

for the second operation.

Jaw swelling, mouth opening ability and oral temperature were measured the day before the

surgery, and on the 3rd day after. Pain and bleeding were measured daily for 5 days, starting the

day of the surgery.

Results: The study showed that on the third day after surgery, patients receiving paracetamol had

29% less jaw swelling than patients receiving placebo. In addition, more patients reported that their

pain was less for the surgery when they got paracetamol compared to the surgery when they had

inactive tablets. This was the case when measured immediately after surgery, and 1 and 2 days

after.

Answer the following questions about above information from the study by Lokken and Skjelbred:

a) Write a possible hypothesis for this study using the ‘If, then’ formalized format

b) What is the dependent variable and how did the researchers operationalize it?

c) Why is blinding necessary in this study?

d) A fellow student reads the study and concludes “Paracetamol is preferable to aspirin for

any oral surgery”. Is this an appropriate conclusion? Explain your reasoning.

Answer 1

a) Write a possible hypothesis for this study using the ‘If, then’ formalized format (3 marks)

-> Hypothesis:

Ho: The inflammatory response to surgical removal of a non- erupted third molar is not significantly reduced if Paracetamol is used than other inactive tablets

H1: The inflammatory response to surgical removal of a non- erupted third molar is significantly reduced if Paracetamol is used than other inactive tablets

b) What is the dependent variable and how did the researchers operationalize it? (4 marks)

We want to measure if paracetamol is effective in reducting inflammation

So,

Dependent variable : If paracetamol reduce inflammation = 0/1 (binary variable)

Independent variables : Jaw swelling, mouth opening ability, oral temperature, Pain and bleeding

c) Why is blinding necessary in this study? (3 marks)

Blinding is necessary so that there is no bias in determining the actual effectiveness of tablets.

If we tell patients they were given inactive tablets, they will stop responding to the effect of tablets

and if we tell doctors about patients given inactive tablets, they will stop examining these patients appropriately.

It will introduce unnecessary psychological bias.

d) A fellow student reads the study and concludes “Paracetamol is preferable to aspirin for

any oral surgery”. Is this an appropriate conclusion? Explain your reasoning. (5 marks)

No, this conclusion is wrong because we are only measuring the signifcance of paracetamol and not comparing it with any other anti-inflammatory drug.

There are many other drugs, why conclude about Aspirin.

We will have to conduct seperate experiment to conduct comparison of these two, and then only we can conclude.

Please rate my answer and comment for doubt, thanks.