Filling accuracy and imprecision of commercial evacuated sodium citrate coagulation tubes

Current recommendations advocate that blood tubes for coagulation testing should be filled not less than 90% of their nominal filling volume, since under- or over-filling >10% may generate unreliable results of some hemostasis assays. This study was hence aimed to explore filling accuracy and precision of commercial blood tubes. Between-lot variations of 3 different lots (20 tubes per lot) of 3.2% citrate blood tubes manufactured by Becton Dickinson, Greiner and Kima were studied. One additional lot from each manufacturer was assessed in triplicate (three series of 20 tubes), to assess within-lot variation. All tubes were first weighed empty and then filled with distilled water by a syringe, under ideal filling conditions. Filled tubes were weighed again, in duplicate. For each 20 tubes series, mean bias (deviation from the ideal tube filling volume) and imprecision (coefficient of variation; CV%) were calculated. All biases were within ±10%. Within-lot and between-lot variation in filling volume was acceptable, and comprised between 0.4 and 2.4%. Greiner tubes were the most accurate (bias, ?1.0 to 2.4%), followed by Kima (bias, ?7.8 to ?5.9%) and Becton Dickinson (bias, ?9.6 to 3.3%) tubes. The highest between-lot difference was noted for Becton Dickinson tubes (up to 12.9%), followed by Greiner and Kima tubes (up to 3.4 and 1.8%, respectively). Although coagulation tubes filling accuracy was within ±10% for all three tested manufacturers, the overall bias was found to be variable among manufacturers and lots. Major effort shall be made by blood tube manufacturers for improving standardization of their products.     

Risk factors for patient‐reported medical errors in eleven countries

Objectives The aim of this study was to identify common risk factors for patient‐reported medical errors across countries. In country‐level analyses, differences in risks associated with error between health care systems were investigated. The joint effects of risks on error‐reporting probability were modelled for hypothetical patients with different health care utilization patterns. Design Data from the Commonwealth Fund’s 2010 lnternational Survey of the General Public’s Views of their Health Care System’s Performance in 11 Countries. Setting Representative population samples of 11 countries were surveyed (total sample = 19 738 adults). Utilization of health care, coordination of care problems and reported errors were assessed. Regression analyses were conducted to identify risk factors for patients’ reports of medical, medication and laboratory errors across countries and in country‐specific models. Results Error was reported by 11.2% of patients but with marked differences between countries (range: 5.4–17.0%). Poor coordination of care was reported by 27.3%. The risk of patient‐reported error was determined mainly by health care utilization: Emergency care (OR = 1.7, P < 0.001), hospitalization (OR = 1.6, P < 0.001) and the number of providers involved (OR three doctors = 2.0, P < 0.001) are important predictors. Poor care coordination is the single most important risk factor for reporting error (OR = 3.9, P < 0.001). Country‐specific models yielded common and country‐specific predictors for self‐reported error. For high utilizers of care, the probability that errors are reported rises up to P = 0.68. Conclusions Safety remains a global challenge affecting many patients throughout the world. Large variability exists in the frequency of patient‐reported error across countries. To learn from others’ errors is not only essential within countries but may also prove a promising strategy internationally.     

It Finally Happened to Me

It finally happened to me: I was sued for malpractice by the family of a patient who had died suddenly. My inner turmoil in the aftermath of this traumatic event affected me deeply. While I was an experienced family doctor dedicated to patient-centered medicine, the event challenged my customary approach to my patients. I share three vignettes from my practice that describe my inner dialogue both “preprosecution” and “postprosecution” and explain how I acted in each case.     

Classifying errors in preventable and potentially preventable trauma deaths: a 9-year review using the Joint Commission's standardized methodology

Background

Benchmarking and classification of avoidable errors in trauma care are difficult as most reports classify errors using variable locally derived schemes. We sought to classify errors in a large trauma population using standardized Joint Commission taxonomy.

Methods

All preventable/potentially preventable deaths identified at an urban, level-1 trauma center (January 2002 to December 2010) were abstracted from the trauma registry. Errors deemed avoidable were classified within the 5-node (impact, type, domain, cause, and prevention) Joint Commission taxonomy.

Results

Of the 377 deaths in 11,100 trauma contacts, 106 (7.7%) were preventable/potentially preventable deaths related to 142 avoidable errors. Most common error types were in clinical performance (inaccurate diagnosis). Error domain involved primarily the emergency department (therapeutic interventions), caused mostly by knowledge deficits. Communication improvement was the most common mitigation strategy.

Conclusion

Standardized classification of errors in preventable trauma deaths most often involve clinical performance in the early phases of care and can be mitigated with universal strategies.     

FIP Perspectives: Realising global patient safety goals requires an integrated approach with pharmacy at the core

Patient safety is becoming increasingly recognised as a top priority for action that requires a collective and coordinated response. The leading cause of harm or injury in health care systems is medication errors. As medicines experts, the pharmacy workforce plays a key role in minimising medication errors and mitigating the global challenge of patient safety. Pharmacists’ involvement in ensuring patient safety is crucial. Pharmacists are charged with the responsibility to ensure that when a patient receives and uses a medicine, it will not cause harm or death. The International Pharmaceutical Federation (FIP) recognises the critical role the pharmacy plays in realising global, regional and national patient safety goals; and works with its partners, stakeholders and members around the world to advocate for the role of pharmacy in achieving this global patient safety agenda and to envision a world of safe access to medicines and care.     

Regression calibration for models with two predictor variables measured with error and their interaction,using instrumental variables and longitudinal data

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured‐with‐error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) – outdoor fine particulate matter and cigarette smoke – and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE ₄, outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory. Copyright © 2013 John Wiley & Sons, Ltd.     

螺旋断层放射治疗胰腺癌摆位误差分析

目的分析在兆伏级电子计算机断层扫描(MVCT)图像引导下采用螺旋断层调强放疗技术治疗胰腺癌患者的摆位误差,并计算计划靶区(PTV)的边界(margin)外放。方法行MVCT图像扫描,将扫描获取的MVCT图像与计划CT图像进行配准,记录左右(X)、头脚(Y)、腹背(Z)轴方向和横断面旋转(roll)方向的误差值,并对误差值进行分析计算。结果共行592次MVCT扫描。X、Y、Z和roll方向摆位误差值分别为(-0.5±2.8)mm、(-1.1±6.4)mm、(6.0±4.4)mm和(-0.2±0.7)°。X、Y和Z 3个方向上的平均误差小于5 mm,所占比例分别为97.13%(575/592)、88.01%(521/592)和37.84%(224/592),roll方向旋转误差小于1°,所占比例为93.92%(556/592)。根据公式得出在X、Y和Z 3个方向PTV的边界外放间距值分别为5.2、9.9和7.5 mm。结论对MVCT图像引导下行螺旋断层放射治疗胰腺癌患者的摆位误差数据分析,为提高放射治疗精度及疗效,推荐胰腺癌放疗在X、Y和Z三维方向上CTV到PTV的margin外放值分别为5、10和8 mm。     

摆位误差对肝癌立体定向放射治疗剂量学的影响

目的:在锥形束CT（CBCT）图像引导下,测量立体定向放射治疗（SBRT）中肝癌的摆位误差,并讨论摆位误差对靶区PTV和危及器官（OAR）剂量的影响。方法:回顾性分析接受SBRT的肝癌患者13例,每日放射治疗前行CBCT扫描,与计划CT图像进行灰度配准,根据肿瘤靶区及OAR位置获取患者移床参数,在计划系统中计算剂量分布,并分析移床参数对靶区PTV、OAR剂量和均匀性指数（HI）、适形度指数（CI）等一系列剂量学参数的影响。结果:校正后X、Y、Z方向上的摆位误差分别为（0.47±2.00）、（1.54±4.16）、（0.10±2.77） mm,Y方向上的摆位误差较大。相对于最小位移,最大位移对靶区、HI和CI影响大;对于OAR,与原始计划相比,左肾、小肠最大位移的剂量分布在Dmean、Dmax上具有统计学意义,右肾最小位移的剂量分布在Dmean上具有统计学意义。结论:≤3 mm的摆位误差对靶区剂量的影响比>5 mm的影响小,但对于最小剂量和覆盖率仍然影响显著。应该尽可能减小摆位误差,以实现精确放疗。