Review articles
 

By Ms. Sidrah Mohammad , Mr. Muhammed R Siddiqui
Corresponding Author Ms. Sidrah Mohammad
University of Liverpool, - United Kingdom
Submitting Author Mr. Muhammed R Siddiqui
Other Authors Mr. Muhammed R Siddiqui
Guildford Hospital, 23 Malvern Road - United Kingdom TN24 8HX

DERMATOLOGY

Paediatrics, Dermatitis, tacrolimus

Mohammad S, Siddiqui MR. The Efficacy of Using Tacrolimus Ointment on Children with Atopic Dermatitis. WebmedCentral DERMATOLOGY 2012;3(7):WMC003605
doi: 10.9754/journal.wmc.2012.003605

This is an open-access article distributed under the terms of the Creative Commons Attribution License(CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
No
Submitted on: 29 Jul 2012 02:57:05 PM GMT
Published on: 30 Jul 2012 05:58:35 PM GMT

Abstract


Background: Tacrolimus ointment, an immunosuppressant, is a second line treatment for atopic dermatitis, which is prescribed when corticosteroids have no effect or the adverse effects are very severe. Objective: To carry out a structured review on the efficacy of using tacrolimus ointment on children with atopic dermatitis, by comparing the efficacy of tacrolimus ointment against a vehicle (placebo). Method: Databases such as Medline, Pubmed, and Scopus were searched for published studies on atopic dermatitis and tacrolimus ointment. Key terms used were: dermatitis, eczema, protopic, tacrolimus, and ointment. Also, Google scholar and BMA search engine were searched via free text for literature. Various books from the University of Liverpool library were read for background reading. Results: Three key studies were identified from the search method carried out. All three studies were double-blind, randomised, vehicle controlled trials that used similar methods to assess the efficacy of using tacrolimus ointment on children with atopic dermatitis. Even though different measurement tools were used within each study to assess outcomes, all three studies reported that tacrolimus ointment was significantly more effective than the vehicle control for treatment of atopic dermatitis. Conclusion: Tacrolimus ointment is effective to use on children with atopic dermatitis.

Introduction


In the UK, seven million people are affected by skin conditions 1.  One of these conditions is eczema.  In the UK, 1 in 12 adults and 1 in 5 children have eczema 2, 3.

For people living with eczema, everyday tasks take on a new meaning.  From clothes shopping, showering, to sleeping, extra care needs to be taken to cover up symptoms and avoid triggering flare-ups.  Having eczema can be a burden for parents 4 and can lead to “sleep deprivation, lack of concentration, and impaired school-work productivity 5” in patients. The stigma that comes with this condition can affect an individuals confidence levels and their self perception of their image, especially when in public 5.

Eczema is an inflammation of the skin 6, 7.  The word ‘eczema’ is derived form the Greek word ekzein meaning to boil 8.  The words ‘Eczema’ and ‘dermatitis’ are used interchangeably 9, 10.  The table below shows the common symptoms of eczema.

see Illustration 1

The rash is symmetrical but not contagious 6.  The different types of eczema are have been described elsewhere 11, 12, 13, 14, 15, 16.

This review is looking at atopic dermatitis in children.

Atopic dermatitis is one of the more common types of dermatitis that affects approximately 20% of the population 19, 17.  Hanifin and Rajka 18 (1980) first came up with criteria that would define this condition.  Over the years, its incidence rate has increased more in developed countries than in undeveloped countries 19, 20.

Atopic Dermatitis initially appears in childhood and in 70% of children it clears completely by the age of 12 6, 19.  It is called ‘atopic’, meaning hereditary, as 70% of cases are due to family history. It is also associated with hay fever and asthma 9, 17.    There are approximately 23 outcome measurement tools, but so far only three of these have been validated 21, 22, 23.

See Illustraions 2,3,4

The exact cause of atopic dermatitis is unknown, but there are two main theories of how it is could be caused and are broadly classified into immunological and autonomic imbalance10,12.

Atopic dermatitis also has an impact on society. In 2001, Emerson et al 24 estimated that “the annual cost of atopic dermatitis in children aged 1±5 years was £47million (£17 million spent on consultations, £13million on prescribing, and £17 million spent by families) 24.”

No cure is yet known, but there are many treatments available depending on the severity of the condition.  For children with atopic eczema, the following treatments have been recommended by the National Institute of Clinical Excellence 25.

see Illustration 5,6

Initially, for all severities of eczema, emollients are first recommended which cost the NHS approximately £16million per year 26.  Starting at a mild strength, corticosteroids are prescribed as a first line medical treatment. If neither emollients nor corticosteroids are effective, then topical calcineurin inhibitors are prescribed.  This review is looking at the efficacy of the topical inhibitor, tacrolimus ointment (commercially known as PROTOPIC®) 27.

“In 1999, tacrolimus ointment was approved for the treatment of atopic dermatitis in Japan. It was then introduced to the United States in 2000, and Europe in 2001 28.”  Tacrolimus is primarily an immunosuppressant which was used initially in kidney and liver transplants to avoid rejection of the organ by the body 29. It is now used externally on the skin as a second line treatment for atopic dermatitis when people do not respond well to steroids 30. The main side effects of the use of protopic are skin burning on application and pruritus (itching) 30.  Tacrolimus ointment has been shown to inhibit T-lymphocyte activation, but its pharmacology in atopic dermatitis is yet unknown 30.  This review will assess the efficacy of tacrolimus ointment on children with atopic dermatitis.

Methods


Background reading was carried out on the topic using Google Scholar and BMA search engine via free text, as well as through various books from the University of Liverpool library.  The National Institute of Clinical Excellence (NICE) website 25 was accessed for the current guidelines on the treatment of atopic dermatitis in children.  In addition, the guidelines for the use of tacrolimus ointment were read on the manufacturers website 27 as well as the package leaflet 31 issued with the ointment.  To acknowledge what patients with eczema go through, personal experiences were viewed through Patient UK 32, National Eczema Society 2, National Eczema Association 33, Medinfo 34, and people who had or still have some form of the condition were approached.  Databases such as Medline, Pubmed, and Scopus were searched for published studies on atopic dermatitis and tacrolimus ointment.  Key terms used were: dermatitis, eczema, protopic, tacrolimus, and ointment.  Searches were focused using mesh terms and relevant searches combined using Boolean operators 35. Table 6 outlines the search terms and databases used.

 see illustration 7

*cannot limit to full text

Abstracts of these studies were read. The following criteria were applied to each study.

see illustration 8

The studies identified were then cross referenced and journals were electronically searched.  The identified studies were then critically appraised to assess their reliability and validity using criteria adapted from Crombie 36 and CASP website 37.

Abstracts of the 29 potentially relevant studies were read, and studies which did not fit the inclusion criteria were excluded. Threee studies were reviewed 38, 39, 40. Through cross referencing and searching journals electronically no further relevant studies were identified. 

 see Illustration 9,10

Results


The table below shows the results of critically appraising the studies.

See Illustrations 11,12

All studies were double-blind randomised controlled trials. Each study was ethically approved by institutional review boards at each centre and consent gained from guardians of the patients.  Studies 2 and 3 justified the sample size they used whilst study 1 did not.  Within the studies, the treatment and vehicle groups were similar at baseline, and the reasons why participants discontinued the trials were reported.  Intention-to-treat analysis was only mentioned in study 2, and is therefore unknown if studies 1 and 3 used this method of analysis or not.  The results from the studies are reliable as they agree with each other, and the outcomes are relevant to clinical practice, regarding the use of tacrolimus ointment for atopic dermatitis on children.

The studies carried out similar trials where patients were treated with tacrolimus ointment or a vehicle.

see Illustration 13,14,15

see Illustrations 16,17,18

Studies 1 and 2 used the same age group and excluded participants with >30%BSA, whereas study 3 included participant with up to 100%BSA but excluded 2-6 year olds.  Each study used the same diagnostic criteria and excluded children who had conditions that would affect the use of protopic.

The primary outcome for each study was the overall improvement of eczema, decided by the clinician comparing pre and post treatment of %BSA affected.  The secondary outcome was the safety of using tacrolimus ointment.

see illustration 19,20,21

Each study found tacrolimus ointment to be significantly more effective than the vehicle control, but as stated in study 1, no significant difference was found between the different concentrations of tacrolimus ointment used. 

see Illustrations 22,23

Each study reported a greater improvement in extent and severity of atopic dermatitis (by means of an EASI score which was calculated pre and post treatment) in the treatment groups compared to the vehicle group.  To assess the safety of the treatment, adverse events were recorded.  In addition, studies 1 and 3 took blood samples from participants to measure safety of the ointment.  In 90% of blood samples taken by study 1, no measurable tacrolimus concentration in the blood was observed concluding that it is safe to use.  Similar results were reported in study 3.  On the whole, the main adverse effects recorded by each study were skin burning and pruritus which were due to application of the ointment. These declined quickly after the first few days of the trial.   Table 14 shows the EASI and pruritus results from each study.

 see illustrations 24,25

Study 3 carried out a follow up of 47% (82/173) of its patients, who reported feeling ‘much better’ at the end of treatment, for time of recurrence of atopic dermatitis.  They reported that 79% (65/82) had recurrence of their atopic dermatitis when treatment had been stopped.

Overall, the results of all three studies agree with each other, and come to the same conclusion that tacrolimus ointment is significantly more effective than a vehicle control for the treatment of atopic dermatitis on children.

Discussion


All three studies were randomised, vehicle controlled trials, with an aim to assess the effectiveness and safety of using tacrolimus ointment as a treatment on children with atopic dermatitis. All studies were multicentre studies conducted in the US. This method of recruitment represents a wide population and limits selection bias of participants.  However, studies 2 39 and 3 40 only included participants with a maximum of 30% body surface area affected with atopic dermatitis therefore the children used in these studies will not be representative of all children with atopic dermatitis. A strength of study 1 38 is that it eliminated this participant selection bias by not setting a maximum percentage of body surface area affected as entry criteria.  The main difference between the methods of each study was the concentration(s) of tacrolimus ointment used. Studies 1 and 3, which directly compared different concentrations of tacrolimus ointment and vehicle, found no overall statistical difference in efficacy between the different ointment concentrations used.  However in study 3, evaluations of the head and neck region suggest that the higher concentrations (0.1% and 0.3%) may be more effective than 0.03% concentration.  This suggests that the lower concentrations (0.03%) of tacrolimus ointment are as effective as the higher concentrations. A drawback of study 1 is that there is no mention of a power calculation, therefore it is not known if the sample size used was large enough to represent the population being studied. Nevertheless, studies 2 and 3 justified the sample size used by the means of a power calculation, both at a power of 80% and a 2-sided 0.05 significance level, with study 3 estimating double the percentage success rate estimated by study 2. (Study 2; vehicle 25% and treatment 40% success, study 3; vehicle 50% and treatment 80% success).  It is important to have the correct sample size so that it is representative of the population being studied. Central computer generated randomisation was used in studies 2 and 3 to randomly allocate patients to treatment and vehicle groups.  This method eliminated selection bias as all patients had an equal chance of being placed in either of the intervention groups.  In addition, study 3 also used block randomisation.  This reduced the chance of all participants from one centre being placed in the same intervention group.  Study 1 suggests that patients were randomly allocated to groups but it does not elaborate on how this randomisation took place which could lead to bias depending on the method used.  Despite this, study 1 stratified the patients into age groups before randomisation.  This eliminated age as a confounding factor.  In comparison, studies 2 and 3 carried out no stratification.  After randomisation, in each study the groups were balanced in terms of gender, race and number, which made them comparable at baseline. The same treatment method was used within each study; the ointment given was applied twice daily to the affected areas of the body.  Treatment bias was eliminated as all patients, caregivers, investigators and clinical staff were blinded in each study. However, it is mentioned in study 3 that the department of pharmaceutical sciences who prepared the study medication was not blinded.  This would introduce bias if their staff had come into contact with patients during the study or if the company had analysed the results. All three studies reported that clinical improvement was noticeable for treated patients within the first two weeks. Study 3 stated that differences between the treatment and vehicle groups were significant by the eighth day of the trial.  Due to this, even though it was intended to eliminate treatment bias from the study by double-blinding, bias could have been introduced depending on whether investigators were able to distinguish between the groups based on improvement of the condition due to the treatment.  Furthermore, the studies do not mention how many clinicians there were who carried out the assessments, as if there were two or more assessors, then inter-observer consistency and therefore reliability of the results needs to be questioned. Even though the studies used different measurement tools, in the end they reached the same outcome; that tacrolimus ointment is effective and safe to use in paediatric patients with atopic dermatitis.  In each study, post treatment, the percentage of body surface area affected by atopic dermatitis was lower in the treatment groups compared to the vehicle groups.  Out of the validated outcome measurement tools, only EASI 21 which evaluates the extent and severity of atopic dermatitis was used in all studies. Each study reported that the EASI 21 score was significantly lower, at the end of the trial, in the treatment groups compared to the vehicle-controlled groups. This suggests that tacrolimus ointment was more effective in reducing the severity and area affected by eczema than the vehicle ointment. Each study also carried out an Investigators Global Atopic Dermatitis Assessment 21 but used slightly different scales to score the outcomes. According to Schmitt et al 21 this new means of outcome measurement is only partly validated and more research needs to be carried out on its validity. Study 1 had a 71% drop out rate in the vehicle group due to lack of efficacy of treatment. However, all participants who received at least one application of the ointment were included in the analysis so this should not affect the results.  For some unknown reason, in their analysis, study 1 included a 15 year old patient who was treated with 0.03% ointment in a similar designed adult study. Thus reducing the reliability and therefore validity of their results.  Only study 2 analysed the results with intention-to-treat.  Out of the three studies, study 3 had the lowest overall drop out rate of 10%. During the two week follow up carried out by study 3, 79% of the patients had a recurrence of atopic dermatitis, due to stopping of the treatment.  This suggests that tacrolimus ointment may not be effective in the long term, as when it is not used, the eczema flares up again.  Questions that would need to be asked are ‘for how long is this treatment effective to use?’ and ‘for what length of time does it need to be applied to stop recurrence of atopic eczema?’  Does it need to be used for life to keep the condition under control? Based on these studies, tacrolimus ointment has been shown to be clinically effective and safe for treatment of atopic dermatitis in children 2-16 year olds. However the longest trial was only carried out for 12 weeks (study 1), therefore the long term effectiveness of using tacrolimus ointment for atopic dermatitis cannot be concluded from these studies. Two long term non-comparative studies, one carried out by Kang et al 41 (for 12 months) and the other by Hanifin et al 42 (for four years), provide an insight on the long term effect of the tacrolimus ointment reporting that there is no loss in efficacy and no increase in adverse effects with prolonged use. Finally, all three studies were sponsored by the same pharmaceutical company.  Studies that are company sponsored tend to have positive results 43, 44.  As well as this, within each study, some of the investigators are full time paid employees of either the drug manufacturing company or the company that sponsored the study (see appendix 2).  This could lead to the reliability of the results being questioned. All three studies were carried out in the US therefore the results cannot be generalised in other countries so similar trials need to be conducted in different countries and see if the same results are found.  Also the children used in the studies may not be representative of all children with atopic dermatitis.  This is because these children were chosen as they had a level of atopic dermatitis which interested the investigators. Even though there are theories on how tacrolimus ointment works, the exact mechanism is not yet known.  By understanding this, it will help understand its efficacy and further treatment of atopic dermatitis. All the studies reviewed concluded that tacrolimus ointment is effective to use.  However, the long term efficacy and therefore safety of its use is unknown and long term cohort studies need to be conducted. So far, seven patients have been diagnosed with cancer whilst using this treatment.  Even though there is no proven link between tacrolimus ointment and cancer, the Food and Drug Administration (FDA) have not ruled out the possibility of a potential risk of cancer and as a result, a warning box is displayed on all drug labelling and the potential risk is the first thing patients are told by many clinicians 45. To further the validity of results, validated measurement tools should be used in future studies to assess the outcomes of the treatment. As only studies in the English language were looked at, this biases the search for studies as negative results are more likely to be published in other languages 46.  As not all research is published, by only looking and published papers, my search was limited to the number of studies available.  Searches were also limited to availability of full text and therefore, all potential available literature was not looked at.  Therefore, the search strategy I carried out would bias my review.  To improve my search strategy in the future, gray literature and the Current Controlled Trials Database would be looked at, hand searching of journals will be carried out, and experts in the field will be contacted for more information.

Conclusion(s)


The studies reviewed concluded that tacrolimus ointment is effective to use as a treatment for atopic dermatitis on children.  Although my question on the efficacy of his treatment has been answered, there are still many unanswered questions; the main one concerning the long term safety of using this ointment.  As yet, there have not been any studies conducted - extending the current four year span. In order for the true and complete benefit of tacrolimus ointment to be assessed, a study running for longer than at least five years is required, and the final choice made between the importance of either short term efficiency or long term safety. 

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