THERAPY WORKSHEET Citation: Are the results of this single preventive or therapeutic trial valid? Was the assignment of patients to treatments randomised? Was the randomisation list concealed? Was follow-up of patients sufficiently long and complete? Were all patients analysed in the groups to which they were randomised? Were patients and clinicians kept “blind” to treatment? Were the groups treated equally, apart from the experimental treatment? Were the groups similar at the start of the trial? Are the valid results of this randomised trial important? SAMPLE CALCULATIONS Occurrence of diabetic neuropathy at 5 years among insulin-dependent diabetics in the DCCT trial Usual insulin Intensive insulin regimen regimen control event experimental rate (CER) event rate (EER) 9.6% 2.8% Relative risk reduction (RRR) Absolute risk reduction (ARR) Number needed to treat (NNT) CER – EER CER CER-EER 1/ARR 9.6% - 2.8% 9.6% = 71% 9.6% - 2.8% = 6.8% 1/6.8% = 15 patients 95% CI * 4.4% to 9.2% 11 to 23 * 95% confidence interval (CI) on an NNT = 1/(limits on the CI of its ARR) = CER (1 CER) EER (1 EER) 0.96 0.904 0.028 0.972 1.96 1.96 2.4% 730 711 # ofControlPts # ofExperPts YOUR CALCULATIONS CER EER Relative risk reduction (RRR) CER – EER CER Absolute risk reduction (ARR) CER-EER Number needed to treat (NNT) 1/ARR 95% CI Can you apply this valid, important evidence about therapy in caring for your patient? Do these results apply to your patient? Is your patient so different from those in the study that its results cannot apply? Is the treatment feasible in your setting? What are your patient’s potential benefits and harms from the therapy? Method I: f Risk of the outcome in your patient, relative to patients in the trial. Expressed as a decimal: ______ NNT/f = ______ / ______ = ______ (NNT for patients like yours) Method II: 1/(PEER x RRR) Your patient’s expected event rate if they received the control treatment (PEER) = ______ 1/(PEERxRRR) = 1/________ = ______ (NNT for patients like yours) Are your patient’s values and preferences satisfied by the regimen and its consequences? Do your patient and you have a clear assessment of their values and preferences? Are they met by this regimen and its consequences? Additional notes: Sample scenario, search, completed worksheet and CAT for evidence-based complementary medicine Therapy: Clinical Scenario A woman comes to see you concerning her son who has attention deficit disorder with hyperactivity. As she does not like the thought of medication, the child is currently untreated. She has obtained leaflets from a parents' group called "Action on Hyperactivity" which suggests that hyperactivity can be caused by "hidden allergies" to common foods. They recommend a "few foods, low sugar, diet". The mother asks whether she should put her son on the diet. You are tempted to say "try it and see" but take into consideration that restricting a child's diet unnecessarily is generally unwise for both health and social reasons. Also, you know of some other children with hyperactivity in your practice and are interested in the possibility of any treatment which would be inexpensive, safe and have good parent acceptability. You pose the questions "In children with hyperactivity, does any form of dietary modification improve behaviour?" Searching terms and evidence source: You search the Cochrane Library for "diet" or "food" or "allergy" with "hyperactivity" or "attention deficit". You find bibliographic details of one review but this is from 1983. There are a number of randomised trials listed in the Cochrane Controlled Trials Register so you decide to have a look at these. Many concern the exclusion of food additives (the "Feingold" diet). You don't consider these pertinent to the task in hand. One trial (Wolraich ML, Lindgren SD, Stumbo PJ, Stegink LD, Appelbaum MI, Kiritsy MC. Effects of diets high in sucrose or aspartame on the behavior and cognitive performance of children. N Engl J Med 1994;330:301-7) shows no effect of sugar and artificial sweeteners on behaviour of either normal children or those said by their parents to be "sugar-sensitive." This casts some doubt on the low sugar element of the suggested diet. However, you also find a number of articles which look interesting from the point of view of food exclusion. Scanning the abstracts, you find four papers in which children are first tried on an exclusion diet and then "responders" tested with double-blind, placebocontrolled food challenges. Response rates for the uncontrolled exclusion diet are up to 85% and food sensitivity is usually confirmed in the double-blind trial. (Boris M, Mandel FS . Foods and additives are common causes of the attention deficit hyperactive disorder in children. Ann Allergy 1994;72:462-8; Carter CM, Urbanowicz M, Hemsley R, Mantilla L, Strobel S, Graham PJ, Taylor E. Effects of a few food diet in attention deficit disorder. Arch Dis Child 1993;69:564-8; Egger J, Carter CM, Graham PJ, Gumley D, Soothill JF. Controlled trial of oligoantigenic treatment in the hyperkinetic syndrome. Lancet 1985;1:540-5) You also find two trials which seem to compare a dietary approach to control on a randomised basis. One of these is in German. The abstract suggests a positive result but language difficulties prevent you reading further. (Schulte Korne G, Deimel W, Gutenbrunner C, Hennighausen K, Blank R, Rieger C, Remschmidt H . The influence of an oligoantigenic diet on the behavior of children with attention-deficit hyperactivity disorders. Zeitschrift Fur Kinder Und Jugendpsychiatrie Und Psychotherapie 1996;24:176-183) The other trial is in English and seems to be just what you are looking for. You order this paper from the library. Read the article and decide: 1. Is the evidence from this randomised trial valid? 2. If valid, is this evidence important? 3. If valid and important, can you apply this evidence in caring for your patient?
