Aetiology Of Atopic Eczema
The unusual geographical distribution of KS has long suggested an infective cause. Epidemiological evidence, including the 20 times greater frequency of AIDS-related KS in homosexual men compared with haemophiliacs, suggested a sexually transmitted cofactor. In 1994, Chang et al. described the identification of fragments of a novel herpes virus in a biopsy of an AIDS-related KS lesion.8 KS-associated herpes virus (KSHV), also known as human herpes virus 8 (HHV8), can be identified in virtually...
Rm Herd Morbidity And Cost In Atopic Dermatis
The pathophysiology and clinical features of atopic dermatitis. Williams HC, ed. Atopic Dermatitis. Cambridge Cambridge University Press, 2000 25-40. 2. Williams HC, W thrich B. The natural history of atopic dermatitis. In Williams HC, ed. Atopic Dermatitis. Cambridge Cambridge University Press, 2000 41-59. 3. Williams HC. What is atopic dermatitis and how should it be defined in epidemiological studies Williams HC, ed. Atopic Dermatitis. Cambridge Cambridge University Press, 2000...
Plastic surgery Benefits
There are no systematic reviews or RCTs of the role of plastic surgery in the treatment of cutaneous sarcoidosis however, several case reports were found. In 1970, O'Brien described two patients successfully treated with plastic surgery for lupus pernio.75 In 1984, Shaw etal.76 described a man with a 6-year history of treatment-resistant lupus pernio successfully treated with surgical excision and split skin grafting the result remained good 2-5 years after surgery. Collison et al77 described a...
Background Definition
Systemic lupus erythematosus (SLE) is a multisystem inflammatory disease characterised by the presence of a wide variety of autoantibodies. Skin involvement is common, being present in 55-90 of cases.1 The characteristic skin lesions can be divided into acute, subacute and chronic subsets.2 The acute forms include the malar (butterfly) rash, papular lesions, urticaria, vasculitic lesions, hair loss and painless mouth ulcers. Subacute cutaneous lupus erythematosus (SCLE) is an uncommon form of...
Critically ill patients
In a study of 292 critically ill adult surgical and trauma patients, admitted to hospital for at least 48 hours, patients were randomised to no antimycotic therapy, clotrimazole, 10 mg three times a day, ketoconazole, 200 mg day or nystatin, 2 000 000 units 6-hourly. In this group treatment with three or more antibiotics, APACHE II > 10, and ventilatory support for more than 48 hours significantly predicted yeast colonisation and sepsis. The four groups did not differ significantly with...
Opportunistic mycoses
The opportunistic mycoses include the infections due to Candida, Aspergillus and zygomycete fungi of the genera Rhizopus, Rhizomucor and Absidia amongst others. Infection affecting the skin is uncommon and these infections seldom present to a dermatologist any skin involvement has to be set against the background of widespread and life-threatening disease. These infections often occur in patients with severe defects of either neutrophil numbers or function, such as recipients of stem cell...
Incidenceprevalence
The gut is the major reservoir for Candida yeasts, without causing clinical disease. Newborn babies are normally not colonised. Follow up studies showed that the most important and rapid route of colonisation is from mother to child.1 Among the elderly, 36-78 are colonised with Candida denture wearing, smoking and poor oral hygiene are risk factors for the presence of the yeasts.2 The incidence and prevalence of cutaneous Candida i nfections in the general population is unknown, nor is the...
Further information
Details of the PSGs and other organisations mentioned in this chapter are listed below. For a more comprehensive list of UK-based PSGs contact the Skin Care Campaign. There may be similar organisations in other countries but the authors do not have reliable information on PSGs in other parts of the world. The website http www.patientsupportgroups.org may be helpful. National Eczema Association for Science and Education 1220 SW Morrison, Suite 433, Portland, OR 97205, USA. Tel +503 228 4430 or...
A threat of reductionism
Meta-analysis, which refers to the statistical pooling of results drawn from several studies, is prone to dangerous reductionism in terms of adding together studies that it does not make sense to combine.14,15 Thus, before contemplating playing with any statistics, it may seem sensible not to combine studies of childhood atopic dermatitis with those dealing exclusively with adult atopic dermatitis, as they may belong to a different disease group in terms of the aetiology of treatment...
Comment and clinical implications
The quality of reporting in studies was generally poor, with small numbers of patients. It is Table 17.6 Randomised controlled trials that have evaluated treatments for clinically infected atopic eczema Table 17.6 Randomised controlled trials that have evaluated treatments for clinically infected atopic eczema good or very effective as clearance or marked ments highly significant Trial design, description and follow up Table 17.7 Randomised controlled trials that have evaluated antiseptics for...
Relevant outcomes
Outcome measures used in trials have been reviewed by Finlay.25 Most outcome measures have incorporated some measure of itch, as assessed by a doctor at periodic reviews or patient self-completed diaries. Other more sophisticated methods of objectively recording itch have been tried. Finlay drew attention to the profusion of composite scales used in evaluating atopic eczema outcomes. These usually incorporate measures of the extent of atopic eczema and several physical signs such as redness,...
Aetiology
Contact irritants are the commonest external causes. Hand eczema caused by such irritants, or mild toxic agents, is called irritant contact dermatitis. Causal factors that are less common than irritants are contact allergens. Hand eczema caused by skin contact with allergens is called allergic contact dermatitis. Ingested allergens (for example nickel) may also provoke hand eczema. Water is a contact irritant and thereby an external causal or contributing factor....
Other treatments and nonrandomised trials
An early case series of five patients with acute urticaria following insect stings reported good therapeutic effects of intravenous cimetidine 300 mg initially followed by 300 mg orally four times daily) after ineffective administration of epinephrine (adrenaline), H1 antagonists and corti-costeroids.11 A further report investigated the effect of flunarizine, a calcium antagonist, in the treatment of acute urticaria. In this uncontrolled trial 20 patients received a single 10 mg sublingual dose...
Morbidity and costs
Atopic eczema usually accounts for the worst disturbance in quality of life when compared with other dermatological diseases. Specific aspects of a child's life affected by atopic eczema are7 itch and its associated sleep loss (which can also cause considerable family disturbance) social stigmatisation from other children and parents the need for special clothing and bedding avoidance of activities such as swimming the need for frequent applications of topical treatments and visits to...
Working things out on the basis of mechanism and logic
Many physicians base clinical decisions on an understanding of the aetiology and patho-physiology of disease and logic.10,11 This paradigm is problematic because the accepted hypothesis for the aetiology and pathogenesis of disease changes over time, and so the logically deduced treatments change too. For example, in the past 20 years, hypotheses about the aetiology of psoriasis have shifted from a disorder of keratinocyte proliferation and homeostasis, to abnormal signalling of cyclic AMP, to...
Implications for clinical practice
The choice for an optimal topical steroid treatment schedule cannot be derived from the current literature on hand eczema trials. Evidence from studies on other eczematous diseases may have to be considered. In adults with chronic hand eczema, are oral immunosuppressive agents (ciclosporin, methotrexate, mycophenolate mofetil) better in maintaining a long-term (more than 6 months) reduction of patient- and doctor-rated scores than topical corticosteroids Two RCTs were identified, one of which...
Comment implications for clinical practice
Generally the available therapeutic evidence for acute urticaria is quantitatively and qualitatively weak. RCTs of the therapeutic efficacy of the second-generation antihistamines are lacking, although one would like to consider these the first choice of therapy based on the studies in chronic urticaria.3 There is some evidence that the combination of H1 and H2 antagonists has additional beneficial effects. A short-term intervention with corticosteroids seems to be superior to a treatment with...
Hywel Williams Kim Thomas Dominic Smethurst Jane Ravenscroft and Carolyn Charman
Since at least 47 groups of interventions have been tried in atopic eczema, coverage of all therapy-related issues for atopic dermatitis is not possible, even in a chapter of this size. Instead, we have opted to introduce the evidence base for treating atopic eczema by means of three common clinical scenarios 1. a child with moderately severe atopic eczema 2. a person with clinically infected atopic eczema 3. an adult with severe atopic eczema. Much of the background work and methodology within...
Step 1 Asking an answerable structured question
Developing a structured question that can be answered requires practice. An example of a useless question would be, Are diets any good in eczema . A better question, generated from a real clinical encounter, would be, In children with established moderate-to-severe atopic dermatitis, how effective is a dairy-free diet compared with standard treatment in inducing and maintaining a remission . Such a question includes four key elements 1. the patient population one wishes to generalise to 4. the...
Overreliance on RCTs
Whilst RCTs may be the most robust study design for minimising bias for conventional evaluation of the effectiveness of interventions for skin diseases, they have their limitations.18 In some circumstances, it may be impossible or unethical to perform an RCT. For example, it is unlikely that mothers will agree to be randomised to breastfeeding or bottle-feeding to see whether either prevents atopic eczema. Similarly, it would be impractical to randomise medical students to one form of education...
Methods of search2
Any RCT (meta-analysis, systematic review or Cochrane review) on acute and urticaria or hive or wheal or nettle and rash in electronic databases and time periods as indicated in Chapter 6. Which drugs are efficient and safe in the treatment of acute urticaria The search of the Cochrane Library and the other electronic databases did not reveal a systematic review or meta-analysis on acute urticaria. Recently a consensus report on the management of urticaria appeared as a result of a panel...
The role of consumers
Consumer involvement has been a strong feature of the CSG from the very beginning. This is because skin disease greatly affects the quality of life of the individual and because much of the trial work in skin disease has been dominated by answering questions that are important to the pharmaceutical industry. Consumers help us to redress that imbalance. At present (Autumn 2002) the skin group has 55 groups working on topics, both common and rare, such as acne, alopecia, bullous pemphigoid,...
Effectiveness
Only two RCTs evaluating systemic antibiotics for clinically infected eczema were located.2,7 Oral cefadroxil showed significant benefit over placebo for all clinical and microbiological outcomes.2 Erythromycin acistrate and erythromycin stearate both improved clinical and microbiological outcomes. There was no significant difference between the preparations.7 Two further important RCTs have compared systemic antibiotics with placebo in the treatment of non-clinically infected atopic eczema. In...
Methods of search
Controlled trials dating back to 1977 were located by searching the Cochrane Library, Medline, Embase, Pascal and Jicst-Eplus. In addition, a hand-search was performed on any trial (including uncontrolled trials but excluding single case reports) in major English, German, French, Italian and Dutch dermatology journals. Because of the tendency of hand eczema to develop a chronic or relapsing course, all questions below deal with chronic hand eczema. In the context of this chapter, chronicity can...
Additional empirical criteria Disease definition
Whilst it may seem simple to apply the three criteria of randomisation generation concealment, blinding and ITT to judge the quality of RCTs, it is still uncertain how far these factors can reliably discriminate between good and bad RCTs in dermatology. Other factors that are disease specific and rely on content knowledge expertise are likely to be equally important in determining the quality of some dermatology trials. The influence of such disease-specific factors in dermatology is an area...
Other local treatments for warts
One trial of the pulsed dye laser40 involving 40 patients showed no significant difference in cure rates between four pulsed dye laser treatments at monthly intervals and conventional treatment with either cryotherapy or cantharidin. 5-Fluorouracil and intralesional interferons as treatments for warts are more of historical interest. Four41-44 and six45-50 trials, respectively, were found for these treatments, most dating from the 1970s and 1980s. Evidence provided by all the trials was...
The advantages of wellbuilt clinical questions
A well-formed clinical question has two strong advantages it makes finding the evidence easier and forces the clinician to specify the patient populations to which the evidence can be generalised and the outcomes that are clinically important.2,3 A question like Question 4, 5 or 6 above will certainly lead to answers. However, obtaining the answer would require a considerable amount of time in searching and validating a vast amount of literature. Structuring the question as in Questions 1, 2...
Definition and diagnostic criteria
Atopic eczema is a chronic inflammatory skin condition characterised by an itchy red rash that favours the skin creases such as the folds of the elbows, behind the knees and around the neck. The morphology of the eczema lesions themselves varies in appearance from vesicles to gross lichenification on a background of poorly demarcated redness. Other features such as crusting, scaling, cracking and swelling of the skin can occur.1 Atopic eczema is associated with other atopic diseases such as hay...
ABV chemotherapy versus doxorubicin
We found one small randomised study of 61 patients with extensive mucocutaneous or visceral AIDS-related KS, comparing ABV combination chemotherapy with doxorubicin alone.74 The overall response rate was 88 for 30 patients who received ABV combination chemotherapy and 48 for the 31 patients who received doxorubicin, 20 mg m2, alone. The response rates differed significantly. Toxicity was similar in both arms, but neutropenia (< 1000 x 106 cells litre) was more frequent with ABV (52 ) than...
Consumers and research
Consumer involvement in clinical research is rare in dermatology. Most PSGs have the support and encouragement of research as one of their objectives. Many strive towards finding a cure for their particular condition, however unrealistic this may seem to health professionals. In general, however, PSGs tend to give financial support to projects that researchers have already chosen (i.e. the research agenda is mainly driven by university-based academics). Whilst not disputing their ability to...
Combination chemotherapy in endemic African Kaposis sarcoma
We found a series of three small randomised comparative studies of chemotherapy in Ugandan patients with endemic (African) KS.71-73 Chemotherapy is an important modality of treatment for endemic KS in developing countries without adequate access to radiotherapy facilities. On the basis of a previous small randomised study which found a higher response rate for actinomycin D than cyclophosphamide in patients with endemic (African) KS, a second randomised study compared actinomycin D with a...
Aetiologyrisk factors
It has been recently shown that 20 of the children with steroid rosacea had at least one close blood relative with rosacea. Fair complexion, blond hair and green blue eyes are characteristic of patients with rosacea. In England, for example, 48 of patients with rosacea had this skin type. How this frequency compares with that of the general British population is not known. About 0-1 of coloured people are also affected by rosacea, as reported by an old American...
Groups are different from individuals
Even if the person in front of you is a German woman with acute atopic eczema, the results of the trial may not translate to real clinical benefit to her for several reasons. First, because the treatment effects reported in clinical trials, whether this is a mean change in severity score or proportion of people cleared, refers to groups of people. In a group of patients with a summary treatment effect such as a mean change in SCORAD (SCORing Atopic Dermatitis) of 5 points, there will be some...
Costeffectiveness analysis
Cost-effectiveness analysis (CEA) is one form of pharmacoeconomic analysis that incorporates both costs and outcome. The results of CEAs are Table 11.1 Summary of the advantages and disadvantages of different types of pharmacoeconomic analyses Type of Table 11.1 Summary of the advantages and disadvantages of different types of pharmacoeconomic analyses Type of criterion of value to interpret results May be difficult to measure benefits *Often called cost-effectiveness analysis by health...
Oral treatment
Regarding oral antifungal therapy, Stengel et al. compared fluconazole, 150 mg once weekly, with ketoconazole, 200 mg daily, in an RCT of 158 patients who had different forms of dermatophytosis, including a few with cutaneous candidiasis. Cure rates were similar in the patients with cutaneous candidiasis (fluconazole three of three, ketoconazole two of three).21 In a similar design, fluconazole, 150 mg once weekly, was compared with 50 mg daily. The results for cutaneous candidiasis at one...
Metastatic malignant melanoma
Metastatic, or stage IV, MM is a devastating disease. It is defined by dissemination of the cutaneous tumour to other organs or nonregional lymph nodes. The skin, subcutaneous tissues and lymph nodes are the first site of metastatic disease in 59 of patients. When haematogenous spread to liver, bone and brain occurs the natural history is that of one of the most aggressive of all malignant diseases. For all patients with metastatic disease, the median survival is approximately 7 months 25 will...
Case scenario 3 an adult with severe atopic eczema Questions
What is the role of systemic immunosuppressive therapy Immunosuppressive therapy is generally of proven benefit in the short- and intermediate-term (few months) management of atopic dermatitis. Immunomodulatory therapy (platelet activating factor, immunoglobulins, levamisole, etc.), however, is rarely used. We found immunomodulatory therapy to be poorly reported. We decided that the use of less concrete therapies such as anthelmintics and injections of antibodies antigen complexes should not be...
References
Precancerous dermatoses a study of two cases of chronic atypical epithelial proliferation. J Cutan Dis 1912 30 241-55. 2. Lee M, Wick M. Bowen's disease. Cancer J Clin 1990 40 237-42. 3. Frost C, Green A. Epidemiology of solar keratoses. Br J Dermatol 1994 131 455-64. 4. Vitasa B, Taylor H, Strickland P et al. Association of non-melanoma skin cancer and actinic keratosis with cumulative solar ultraviolet exposure in Maryland watermen. Cancer 1990 65 2811-17. 5. Schwartz R. The actinic...
ABV or BV chemotherapy versus liposomal anthracyclines
Three large randomised controlled trials have compared liposomal anthracyclines (either doxorubicin or daunorubicin) with standard ABV or BV combination chemotherapy. We found one randomised study comparing liposomal daunorubicin (DaunoXome) with ABV and two randomised trials comparing liposomal doxorubicin with standard combination chemotherapy (either ABV or BV).60-62 All three trials assessed response using modified ACTG response criteria and graded toxicity according to standard criteria....
Effectiveness Azathioprine
No systematic review and no RCTs inform us about the use of azathioprine. Its use is confined to certain specialists and, anecdotally, it appears to have limited efficacy. An ongoing RCT has been identified on the Cochrane Skin Group's ongoing clinical trials register (see http www.nottingham.ac.uk muzd) which is due to report in late 2002. Systemic prednisolone is commonly used in short bursts (a few weeks) for severe atopic eczema. The systematic review concluded that the potency of this...
Efficacy
Only four RCTs have been published in full in three papers at the time of this summary (two trials in adults, n 34 and n 260, and two trials in children combined into one, n 403).6-8 It is likely that there are many more unpublished and ongoing studies. In the first study, 34 patients with moderate atopic eczema were randomised within a right-left body comparison study.6 Topical 1 pimecrolimus (syn. with ascomycin) was applied twice daily (n 16) or once daily (n 18) and compared with the...
Photodynamic therapy PDT Efficacy
Four RCTs31-34 of different types of PDT reported varying success. Cure rates ranged from 8 (of patients) to 73 (of warts). One trial31 in 52 adults and children using a left-right design (randomising active and placebo treatments to warts on the left and right side of the body) showed resolution of warts in 40 of participants. In all those that responded to treatment, the warts on the placebo-treated side also resolved. In another trial in 40 adults,32 aminolaevulenic acid (ALA) PDT achieved a...
Antihistamines firstgeneration H1 antagonists and H2 antagonists
Four studies compared the use of H1 and H2 antagonists or a combination. None of these studies had a placebo arm. Two studies compared diphenhydramine with an H2 antagonist (famotidine or cimetidine). Moscati et al. investigated the efficacy of a single-dose intramuscular cimetidine 300 mg with Summary of data from randomised controlled trials of the treatment of acute urticaria Itching, wheal intensity, sedation, wheal extent, overall Improvement on a 3-A point Diphenhydramine significantly...
Intralesional corticosteroids Benefits
One randomised controlled trial (RCT) and one observational comparison study confirm that intradermal injections of triamcinolone acetonide, 5 mg ml by a needle-less injector, produced rapid regrowth of hair in a high proportion of subjects with limited disease, within 4-6 weeks. What are the effects of treatment for patchy alopecia areata In a report of 84 patients using normalsaline controls, 86 of patients treated with triamcinolone responded, compared with...
Emollients and occlusive dressings
Psoriatic plaques are dry, scaly and frequently itchy. Emollients may help to soften psoriatic scale by increasing its water content, either by forming an occlusive layer on the skin surface (for example white soft paraffin) or by an osmotic effect (for example urea containing creams). Most topically applied therapies for psoriasis are formulated in emollient bases but emollients on their own are frequently advocated for psoriasis. They are claimed to reduce dryness, scaling and itch. There is...
Azole drugs
A number of RCTs have investigated the effect of newer azolic drugs in different cutaneous candidiasis variants. One RCT compared sertaconazole 1 and 2 cream in 10 patients, who used each for 28 days. Clinical, microscopic and microbiological parameters were evaluated. The cure was total for 19 out of the 20 patients, demonstrating high efficacy. There were no relapses of infection in any of the cured patients. No local or general effects were recorded during this trial.17 Another RCT enrolled...
Systemic antifungal therapy for tinea capitis in children
Griseofulvin has been the most widely used and the most prescribed treatment for tinea capitis and has served as a standard for the evaluation of any newer agent to be considered for this infection. New drugs being used against other fungal infections in adults, such as ketoconazole, itraconazole, terbinafine and fluconazole, are being considered more frequently for the treatment of tinea capitis. Sufficient pharmacological and pharmaceutical data exist on these five antifungal drugs to make...
Case scenario 1 A child with atopic eczema of moderate severity
Figure 17.1 A child with flexural atopic eczema Figure 17.1 A child with flexural atopic eczema What is the role of emollients Efficacy We found no systematic review for emollients in atopic eczema. Five randomised controlled trials (RCTs) are reported here.1-5 Other studies were excluded because we could not ascertain if they were properly randomised they included conditions other than atopic eczema (for example Newbold6) or they presented only biometric data, the clinical relevance of which...
Singleagent chemotherapy Bleomycin
We found three small uncontrolled phase II trials of bleomycin as single-agent therapy in the treatment of AIDS-related KS and one small non-randomised study comparing singleagent bleomycin with combination ABV chemotherapy.42-45 In one non-randomised phase 11 study of single-agent bleomycin, 30 patients received intramuscular bleomycin, 5 mg day for 3 days every 14-21 days, and another 30 patients received bleomycin by infusion, 6 mg m2 day for 4 days every 28 days.42 The overall partial...
Intralesional chemotherapy
Two uncontrolled phase II studies have examined the effect of treating intraoral, oropharyngeal and laryngeal AIDS-related KS by intralesional injection of vinblastine.16,17 One obtained a 62 complete response rate (16 26 lesions) in 24 patients with AIDS-associated oropharyngeal or laryngeal KS.16 Lesions were injected with vinblastine, 0-1-0-2 mg ml repeated every 4 to 5 weeks until complete response or stable disease. Side-effects included self-limiting pain, and ulceration. In 11 of 24...
Dapsone Benefits
We found no RCTs or controlled trials of dapsone in lupus erythematosus. Belief in the efficacy of dapsone is based on a number of observational studies. These studies report on a total of 55 people with various forms of cutaneous lupus.61-63 Marked improvement was noted in 22 people 50 . The use of dapsone has also been reported in several case reports and particularly in people with unusual forms of lupus, such as bullous lupus and urticarial vasculitis.64-69 Dosage varied from 25 to150 mg...
References for metastatic malignant melanoma
Balch CM, Reintgen DS, Kirkwood JM et al. Cutaneous melanoma. In DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer Principles and Practice of Oncology, 5th ed. Philadelphia Lippincot-Raven 1997 1947-94. 2. Unger JM, Flaherty LE, Liu PY et al. Gender and other survival predictors in patients with metastatic melanoma on Southwest Oncology Group Trials. Cancer 2001 91 1148-55. 3. Crosby T, Fish R, Coles B, Mason MD. Systemic treatments for metastatic cutaneous melanoma. In Cochrane...
References Granlund H. Erkko
Veien NK, Larsen P0, Thestrup-Pedersen K, Schou G. Long-term, intermittent treatment of chronic hand eczema with mometasone furoate. Br J Dermatol 1999 140 882-6. In adults with chronic clinically active hand eczema, do protective or occlusive gloves, barrier-creams, avoidance of allergens and irrititants, and other non-pharmacological interventions lead to better patient- and doctor-rated sign scores than topical steroids 2. English JSC, Bunker CB, Ruthven K, Dowd PM, Greaves MW. A...
Prognosis
The majority of children with atopic eczema appear to grow out of their disease, at least to the point where the condition becomes a problem no longer in need of medical care. A detailed review of prognostic studies reported elsewhere2 concluded that most large studies of well-defined and representative cases suggest that about 60 of childhood cases are clear or free of disease symptoms in early adolescence. However, many such apparently clear cases are likely to recur in adulthood, often as...
Case scenario 2 How should infected atopic eczema be treated
The relationship between Staphylococcus aureus and atopic eczema disease activity has been debated for many years. Most physicians recognise clinically infected eczema as recent onset of weeping, oozing and serous crusting or overt pus overlying the eczematous lesions. In this situation S. aureus is isolated in 90-100 of cases, usually in high numbers.1,2 In around 30 of cases, beta haemolytic streptococci are also isolated.1 Clinical infection is undoubtedly a major problem for some atopic...
Is Eczema Majama
A controlled trial of house dust mite eradication using natamycin in homes of patients with atopic dermatitis effect on clinical status and mite populations see comments . Br J Dermatol 1989 121 199-208. 2. Endo K, Fukuzumi T, Adachi J et al Effect of vacuum cleaning of room floors and bed clothes of patients on house dust mites counts and clinical scores of atopic dermatitis. A double blind control trial. Arerugi Jpn J Allergology 1997 46 1013-24. 3. Tan...
Number needed to treat
Because many interventions in medicine are of only modest effect, their apparent benefit may not be that noticeable after one has tried the intervention on a few patients. One way to understand the magnitude of benefit in relation to baseline risk is to use the concept of number needed to treat NNT .17 This refers to the number of patients that on average you would need to treat in order to see one additional success in the new treatment when compared with standard treatment. NNT is calculated...
