TDM with anti-TNF's was collected. Logistic regression was used to predict factors influencing TDM use. Results 243 respondents participated (51.6% male) of which 237 respondents met inclusion criteria; treating >5 IBD patients and at least 1 with an anti-TNF per month. Of the total respondents, 45% were Consultant Gastroenterologists (GI), 40% IBD Nurse Specialists (CNS) and 15% GI Specialist Registrars (SPR). Of these 237 respondents, TDM was used by 95.7% for secondary loss of response; 71.4% for primary non-response and 53.6% used TDM proactively. Barriers for TDM use were time lag in receiving results (27.1%), lack of awareness of guidelines (15.6%), and cost (11.9%). Clinicians working at a teaching hospital were more likely to use TDM compared to a district hospital (OR 2.6, 95% CI 0.71-9.8). IBD CNS and GI SPR used TDM more often, when compared to Consultant GI (OR 2.6, 95% CI 0.69-10 & OR 1.5, 95% CI 0.3-7.2 respectively). Clinicians practising for >20 years were more likely to check TDM than less experienced clinicians (OR 4.1, 95% CI 0.4-41.8). Clinicians with large volume IBD practice (>50% IBD patients per month) were more likely to check TDM than those seeing fewer IBD patients (OR 45.6,. Proactive TDM was more likely to be used by clinicians working in a tertiary care setting (OR 2.25, 95% CI 0.84-6.05), IBD CNS (OR 1.2, 95% CI 0.6-2.1), clinicians managing large volume IBD practice (OR 10.8, 95% CI 1.2-90) and clinicians with 5-9 years of experience in practice (OR 2.6 & CI 1.04-6.42). Conclusions Large volume IBD centres with more experience of treating IBD patients are more likely to employ treatmentoptimising strategies with TDM. Significant barriers to TDM implementation in the UK are time lag from test to result, lack of awareness of current guidelines and evolving knowledge, cost and less experience. Validation of point of care testing, lower cost assays, and wider dissemination of current evolving paradigms with updated recommendations may further optimise treatment with anti-TNF therapies.

Introduction Doctors are being introduced on air ambulance services in the UK. Meaningful assessment of air ambulance services is difficult owing to inter-service variation. County air ambulance (CAA) (rebranded as Midland's Air Ambulance after this article was written) progressively introduced doctors into their service from 2006 providing an opportunity to gather data and quantify the sample size that will be required to assess their impact on patient survival. Method CAA trauma alerts to Selly Oak Hospital (the main receiving hospital for the service) between 1 January 2006-30 June 2007 were reviewed. Crew composition, mission data and patient notes were examined and the abbreviated injury score 98 and injury severity score were used to calculate the probability of survival. Survival outcome was ascertained at 90 days. Data analysis included survival analysis; Cox regression; logistic regression; tests for association (CI 95%, P<0.05). Post-hoc power calculations were undertaken. Results 299 cases were identified, 186 met the inclusion criteria. The probability of survival ranged between 5.56-99.48%. There was no statistically significant association found between crew composition and survival (P=0.355) and post-hoc power calculations showed 54 258 events would be required to assess this. If accepting 80% power and assuming our proportion of 14% mortality ± 5%, 800 events would be required in each arm of future studies. Conclusions Our post-hoc power calculations revealed that a national or multi-centre study is needed to assess this aspect of aircrew composition in order to prove or discount associations between crew composition and survival at 90 days. Now that a power estimate is available, designing adequately powerful studies will be possible; enabling monitoring the increasing deployment of this expensive resource and examining the effect of doctors on air ambulances. This is of increasing importance to assess as medically-led air ambulance missions increase.