Comparing simulation and threshold approaches when analysing data with probabilities of categories

Objective Constructing categories based on probabilities is not unusual in defining the outcome or the exposure. We compare the threshold approach and the simulation approach in making inferences. Method We used a simple structured example as well as published data to illustrate the difference between the simulation and the threshold approaches. Results We demonstrated that simulation results were different from the threshold approach in estimating the effect of a high‐deductible health plan. For repeat visits, we estimated a statistically significant ratio of incident rate ratio (IRR) 0.78 (95% CI: 0.64, 0.93) for non‐preventable emergency department visits using the simulation approach while the high‐severity category showed no statistical significance with the ratio of IRR 0.98 (95% CI: 0.64, 1.49) using a threshold of 75%. We also demonstrated that none of the threshold values could achieve the results of the simulation approach. Conclusions The simulation approach is preferred over the threshold one when analysing data with probability‐based outcome, exposure and/or other covariates if the size of the data permits.     

Observing decision‐making in the general practice consultation: who makes which decisions?

OBJECTIVE: To investigate opportunities for, and types of decision making in the general practice (primary care) consultation, and examine differences in skills of those doctors who are successful at meeting their patients' preferences and those who are less successful. DESIGN: Observation study of doctor-patient consultations in general practice. PARTICIPANTS: Patients attending for routine appointments in 12 general practice surgeries across Oxfordshire. METHODS: A total of 212 doctor-patient consultations were video-recorded. The patients involved completed a questionnaire to elicit their perceptions of how decisions were made. The video-taped recordings were coded with a new instrument, the Evidence Based Patient Choice Instrument (EBPCI), to classify the number and type of decision-making opportunities arising during each consultation. A total of 149 recordings were coded using the Oxbridge Rating Scale to assess the doctors' consultation styles. RESULTS: There was a range of decision-making opportunities in addition to those involving medical treatment. With the exception of 'fitness for work', decisions were generally 'doctor led'. There was only moderate agreement between patient perceptions of their level of involvement in decision making and the objective ratings using the EBPCI. There was wide variation in the ability of doctors to meet their patients' preferences for involvement. CONCLUSIONS: There are many decisions made in primary care consultations, in addition to those about medical treatments, in which patients could be involved to a greater extent than they currently are. Some doctors are significantly better than others at meeting different patients' preferences for their decision-making role. Patients' perceptions of shared decision making appears to be influenced by the doctors' general consultation skills.     

Elevated Serum Alpha Fetoprotein and Normal Liquor Alpha Fetoprotein Values in Association with an Abdominal Pregnancy

Summary: A case report is described in which abdominal pregnancy was misdiagnosed by ultrasound scanning as a pregnancy within a horn of a bicornuate uterus. Two serum alpha fetoprotein (SAFP) results were greatly elevated and an amniocentesis was performed, the liquor alpha fetoprotein (LAFP) and karyotype were normal. Elective Caesarean section was performed at 38 weeks for a persistent transverse lie and an abdominal pregnancy was found. The outcome was excellent for both the mother and child.
This is the first reported case of amniocentesis and measurement of LAFP in an abdominal pregnancy and confirms abdominal pregnancy as a rare cause of an elevated SAFP.     

Electroporation enhances transfection efficiency in murine cutaneous wounds

Transfection of wounds with DNA-encoding growth factors has the potential to improve healing, but current means of nonviral gene delivery are inefficient. Repeated high doses of DNA, necessary to achieve reliable gene expression, are detrimental to healing. We assessed the ability of in vivo electroporation to enhance gene expression. Full-thickness cutaneous excisional wounds were created on the dorsum of female mice. A luciferase- encoding plasmid driven by a CMV promoter was injected at the wound border. Following plasmid administration, electroporative pulses were applied to injection sites. Pulse parameters were varied over a range of voltage, duration, and number. Animals were euthanized at intervals after transfection and the luciferase activity measured. Application of electric pulses consistently increased luciferase expression. The electroporative effect was most marked at a plasmid dose of 50 micro g, where an approximate tenfold increase was seen. Six 100- micro s-duration pulses of 1750 V/cm were found to be the most effective in increasing luciferase activity. High numbers of pulses tended to be less effective than smaller numbers. This optimal electroporation regimen had no detrimental effect on wound healing. We conclude that electroporation increases the efficiency of transgene expression and may have a role in gene therapy to enhance wound healing.