PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Learning Curve”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources
PubMed1986

Statistical mixture decomposition as a method for type analysis of learning curves.

A method for type analysis of learning curves, based on the statistical mixture decomposition, is described. Some critical points in current data-analytic techniques are discussed. The mathematical rationale of the new method is outlined in a brief sketch. The possibilities of the method are documented by two examples. In the first study, done on simulated lata of a known structure (N = 200, 2 classes), it was possible to distinguish, with an average performance of 82%, between two types, and to reproduce their original curves. In the second study data from experiments in classical eye-lid conditioning in man were analysed (N = 80). The decomposition procedure resulted into the classification into four groups, with pronounced inter-class differences in the course of respective learning curves. The variety of class curves ranges from a group with only few CRs (C1, N = 26), through a group with an initial increase and final decrease in CR frequency (C2, N = 16), a group with an apparently biphasic course of CR frequency (C3, N = 20), to a group with a rapid increase of CR and then stable course of CR frequency (C4, N = 18). The results are consistent with earlier findings concerning the existence of distinct types of learning curves. The problem of interpretation is briefly discussed. The method can be applied principally to any problems, where different types of time development trends of an alternative response are to be distinguished.

Conditioning, Classical↗
PubMed1997

The learning curve and the health care industry.

This article will examine the learning curve and its potential impact on the health care industry. Although the learning curve has traditionally been applied to the manufacturing industry, a labor-intensive industry like health care is a prime candidate for the benefits of the learning curve. Specifically, we will look at past research on the learning curve and discuss what effects learning might have on health care costs and outcomes in the current health care environment.

Accounting↗
PubMed2006

The learning curve in stapes surgery and its implication to training.

OBJECTIVE: To identify the stapedotomy learning curve of two U.K. otolaryngologists. STUDY DESIGN: A retrospective review of the outcome of first 100 stapedotomy operations by each surgeon. Included in the study was a postal survey of the incidence of stapes surgery by U.K. otolaryngologists. SETTING: Two tertiary referral centers. PATIENTS: All ears in which primary stapedotomy was performed for otosclerosis. Nonotosclerotic cases and malleus stapedotomy cases were excluded. INTERVENTION: One surgeon used the technique of small fenestra stapedotomy with either a Teflon-wire or titanium piston but without vein graft interposition, whereas the second used the technique of stapedotomy with vein graft interposition and a Teflon piston. MAIN OUTCOME MEASURES: A moving average with a window of 15 dB was used to plot learning curves for the postoperative air-bone gaps. Using a postoperative air-bone gap of 20 dB or better as a definition of 'success,' the success rates with the increase in surgical experience of both surgeons were plotted on graphs, the learning curves. The end point of the learning curve was defined as the point where the curve reached its peak, and the results were sustainable. RESULTS: There was no clear-cut end point in both learning curves, although it appears that there is a landmark point at 60 to 80 cases for both surgeons. Both surgeons also had one "dead ear" in their first 15 cases. The postal survey showed that some trainers only performed small numbers of stapes surgery, whereas some otolaryngologists who performed stapedotomies regularly were not trainers. CONCLUSIONS: The study supports a learning curve in stapes surgery. To maximize the training opportunity of trainee surgeons, it may be advisable for learning centers to form network to provide target training for the trainee who has demonstrated the necessary dexterity and temperament of an otologist.

Adult↗
PubMed2005

Defining the learning curve for percutaneous nephrolithotomy.

PURPOSE: To define the learning curve for percutaneous nephrolithotomy (PCNL) using three potential surrogate markers of surgical expertise. MATERIALS AND METHODS: The learning curve of an endourologist with no previous experience at performing solo PCNL was studied. Three putative parameters of expertise were reviewed, namely, operating time, fluoroscopic screening time, and radiation dose. Operations were analyzed in cohorts of 15 to determine when a plateau was reached for all three variables. Comparison was then made with the results of a surgeon who had performed more than 1600 PCNLs. Stone type and stone clearance rate were also noted. RESULTS: The mean operating time of the novice surgeon fell to a plateau of 92 minutes after 60 cases, but screening time and radiation dose did not plateau until case 115, when values of 231 seconds and 406 cGy/cm2 were recorded, respectively. The senior surgeon had a mean operating time of 98 minutes and screening parameters equivalent to those of the novice surgeon after 115 cases. The complexity of the stones tackled grew with increasing experience, although stone-free rates remained constant. CONCLUSIONS: This study of the learning curve of a single surgeon suggests that competence at performing PCNL is reached after 60 cases and excellence after 115. Radiation parameters are a valuable tool in the assessment of operative competence.

Clinical Competence↗
PubMed2004

Decomposing serial learning: what is missing from the learning curve?

Our current understanding of serial learning relies on the form of the learning curve and on changes in the serial position curve over repeated study-test trials (Ward, 1937). The averaging of data that produces these functions obscures the detailed history of memory for individual items over the course of study-test trials. Extending Tulving's (1964) analysis of free recall learning, we present a new analysis of serial learning that tracks the acquisition and forgetting of item and order information at the level of individual items. Applying this analysis to two large data sets on serial list learning allows us to discern among hypotheses that are indistinguishable solely on the basis of the learning curve.

Humans↗
PubMed1997

Effect of learning curve on the outcome of external cephalic version.

AIM: The aim of this study was to find out the effect of learning curve on the outcome of external cephalic version (ECV) at term, using tocolytics. The effect of various factors affecting the outcome of ECV was also studied in relation to the learning curve. METHODS: This is a prospective longitudinal observational study of 80 consecutive cases of ECV. They were analysed in relation to outcome, parity, type of breech, placental site and birth weight. The cases were divided consecutively into 4 groups of 20 cases each, in order to analyse the effect of learning curve. RESULTS: The learning curve for ECV is very sharp. The success rate of external cephalic version plateau after the first 20 cases from 45% to about 60%. Only parity and type of breech have a significant effect on the outcome. The success rate is lower for primipara and non-flexed breech. This negative effect is strongest in the first 20 cases and again plateaus after the first 20 cases. The high success rate of multipara and primipara flexed breech is obtained even in the first 20 cases and does not improve with further experience. CONCLUSIONS: The learning curve for ECV is sharp and plateaus after the first 20 cases. Outcome of ECV for patients with favourable factors such as multiparity and flexed breech is not affected by learning curve.

Clinical Competence↗
PubMed2005

Evaluation of the learning curve in ileal pouch-anal anastomosis surgery.

SUMMARY BACKGROUND DATA: We define the learning curve required to attain satisfactory training in ileal pouch-anal anastomosis (IPAA) and identify possible differences in the learning curve for stapled and hand-sewn IPAA surgery. Various studies have addressed the differences in failure rate between stapled and hand-sewn IPAA, but there is no literature that evaluates the differences in attaining satisfactory training in each of these techniques. METHODS: Data were collected from 1965 patients undergoing IPAA surgery by 12 surgeons in a single center between 1983 and 2001. Using ileoanal pouch failure as the primary end point, a parametric survival model was used to adjust for case mix (patient comorbidity, preoperative diagnosis, manometric findings, and prior anal pathology). A risk-adjusted cumulative sum (CUSUM) model was used for monitoring outcomes in IPAA surgery. RESULTS: The 5-year ileal pouch survival was 95.6% (median patient follow-up of 4.2 years; range 0-19 years). Fifty percent of trainee staff demonstrated a learning curve in IPAA surgery. Having adjusted for case mix, trainee staff undertaking stapled IPAA surgery showed an improvement in the pouch failure rate following an initial training period of 23 cases versus 40 cases for senior staff. The learning curve for hand-sewn IPAA surgery was quantified only for senior staff who attained adequate results following an initial period of 31 procedures. CONCLUSIONS: The CUSUM method was a useful tool for objectively measuring performance during the learning phase of IPAA surgery. With adequate training, supervision, and monitoring, the learning curve in IPAA surgery may be reduced even further.

Adult↗
PubMed1996

D2 gastrectomy: lessons from a prospective audit of the learning curve.

A 3-year prospective study of the learning curve for D2 gastrectomy was carried out by one surgeon beginning to perform the operation independently after intensive specialist training. Some 38 patients were treated; there were four postoperative deaths and 22 patients had complications. Postoperative morbidity decreased significantly with time (rS = -0.38, P = 0.02, 95 per cent confidence interval -0.62 to -0.07). The physiological component of POSSUM (Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity) was significantly lower in the third year (median value 15, 16 and 14 for years 1, 2 and 3, n = 31, chi 2 = 7.5, 2 d.f., P = 0.02, Kruskal-Wallis test), but the operative POSSUM scores and the number of lymph nodes found were not decreased (median operative POSSUM score 19, 18 and 21, n = 31, chi 2 = 0.2, 2 d.f., P = 0.91, Kruskal-Wallis test). The results suggest a learning curve lasting about 18-24 months or 15 to 25 procedures before a plateau is reached. Improved results were associated with changes in case selection and operative tactics but not with reduced extent of lymphadenectomy. D2 gastrectomy should be restricted to specialist centres where adequate training and supervision can be provided during the learning curve.

Female↗
PubMed2003

"Learning curves" of cardiac surgery in relation to risk stratification and hospital location.

AIM: The purpose of this study was to determine any significant differences in "learning curves" between private and public hospitals when the same senior surgeon was responsible during the initial phases of open-heart surgery programs development, in relation to risk stratification and hospital location. METHODS: A prospective review of 610 patients records was performed at a newly-opened cardiothoracic program in a public University Hospital (PUH) in the periphery of Greece, and a private institution (PI) with an experienced intensive care unit (ICU) in the capital city of Athens. Preoperative risk stratification, mortality and postoperative length of stay (LOS) were analysed between 1999 to 2001. RESULTS: At PUH 298 patients were operated and 312 patients at PI. There were 136 low risk (EuroSCORE 0-2) and 474 medium and high-risk patients (EuroSCORE > or =3). There was no significantly elevated mortality or learning curve in low risk surgery either at PUH (57 patients with 1 death) or PI (79 patients and 1 death). In medium and high-risk surgery at PI there was no mortality in 68 patients operated by the senior surgeon and no learning curve in all 233 such patients. In 240 medium and high-risk patients at PUH there was a learning curve despite the involvement of the same senior surgeon. In 1999 and 2000 the observed mortality (OM) in 150 patients was 15.33%, EuroSCORE 5.98, and in 2001 in 91 patients OM 3.29%, EuroSCORE 5.95 with p=0.00.8 when "experienced" ICU staff was employed. LOS was significantly reduced in 97 patients in 2001 at PUH (8.7 d +/- 2.81 vs 11.07 days +/- 7.9 in 1999 and 2000, p=0.046) confirming the existence of a learning curve at the PUH. No such change was observed at PI (8.2 days vs 7.8, p=0.45). CONCLUSION: No mortality differences or learning curve characteristics were detected for low risk operations either at PUH or PI. For medium and high risk surgery there appears to be a learning curve in PUH but not in PI despite senior surgeon involvement in both. The presence of an experienced ICU appears to play a critical role in the outcome of operations in newly opened cardiothoracic programs.

Analysis of Variance↗
PubMed2002

Teaching ultrasound-guided invasive procedures in fetal medicine: learning curves with and without an electronic guidance system.

OBJECTIVE: To compare the learning curves of inexperienced junior obstetrics/gynecology registrars for ultrasound-guided invasive procedures on a training model, with and without an electronic guidance system. STUDY DESIGN: Four junior registrars performed their first 100 procedures on a training model with a new electronic guidance system, and four other junior registrars performed their first 100 procedures on the same training model without using the guidance system. All procedures were performed using a free-hand technique. We evaluated the quality of the procedure, which we defined as the time spent with the entire needle clearly visualized on the screen over the total duration of the procedure. We constructed learning curves for the eight junior registrars for comparative analysis. RESULTS: Quality of the procedure increased over time for all trainees. The learning curves were significantly steeper for trainees using the electronic guidance system. Trainees using the electronic guidance system performed better in the middle of their learning curve (procedures 25-75). All trainees reached the same level of quality by the end of their 100 procedures. CONCLUSIONS: The automated electronic guidance system helps faster learning but, after 100 procedures on a training model, both groups reached the same level of quality.

Amniocentesis↗
PubMed2004

Learning curve and stage migration of a radical retropubic prostatectomy series over a 10-y period.

OBJECTIVE: To show the impact of learning curve and patient selection on complication rate and biochemical recurrence-free survival of a UK radical prostatectomy series for localised prostate cancer and to model the influence of common preoperative variables on biochemical recurrence after controlling for learning curve. PATIENTS AND METHODS: From 1989 to 1999, 280 of 350 patients who underwent anatomical radical retropubic prostatectomy (RRP) at our institution had complete records and follow-up of at least 1 y. After exclusions of preoperative staging, factors reflecting the learning curve, early complications and prostate-specific antigen (PSA) outcome were recorded on 217 patients. Procedures before 1995 were compared with procedures after 1995. RESULTS: Comparison of the two groups showed a significant decrease in operating time (mean 152 vs 130 min), blood loss (mean 1500 vs 1000 ml), transfusion rate (83 vs 42%) and hospital stay (mean 7 vs 6 days). Median preoperative PSA changed significantly from 13.2 to 11.5 ng/ml. Only 17% were diagnosed by rectal examination compared to 27% in the early years. The number of clinical T1 tumours increased from 33 to 47%. This did lead to an increase of organ-confined tumours on pathological staging by 25%. Biochemical recurrence-free survival improved significantly after 1995. After controlling for the learning curve PSA and clinical stage were significant predictors of PSA recurrence. CONCLUSION: Time trends of case selection, stage migration and a steep learning curve are shown over a 10-y period. Factors associated with the learning curve as well as case selection have a significant impact on outcome. There may be other as yet not specified factors over time, which have a significant impact on PSA recurrence-free survival. Patients with a PSA of 20 ng/ml and above have a poor outcome and do not appear to be suitable candidates for RRP.

Aged↗
PubMedDate not supplied

[Characteristics of the learning curve in total hip endoprosthesis exemplified by the BiContact prosthesis].

AIM: Total hip arthroplasty is a common operation but there are few data describing the learning curve of this operation. The aim of the presented study is to prove and describe the learning curve in total hip arthroplasty. METHOD: Between 1991 and 1993, 168 patients were included in this prospective study, operated by three surgeons having different experiences in operating total hip arthroplasty. Perioperative complications and postoperative X-rays were analysed. Patients were re-examined clinically and radiologically and by a questionnaire 5 years after operation. RESULTS: Radiological complications of the first 84 operated patients were statistically significantly higher than those of the following 84 patients, except for minimal bone fractures and leg lengthening. The learning curve of all surgeons was finished after 20 operations independent of their experience. Clinical results were not influenced by the learning curve at follow-up. CONCLUSIONS: Regardless of the experience of the surgeon, the learning curve in total hip arthroplasty is finished after about 20 operations for each surgeon. Intensive preoperative planning and exchange of experience inside and outside every clinic will shorten the length of the learning curve.

Adult↗
PubMed2000

Comparison between personal learning curves for abdominal and laparoscopic hysterectomy.

BACKGROUND: To compare personal learning curves for abdominal and laparoscopic hysterectomy. METHODS: The first 200 patients scheduled for abdominal hysterectomy and the first 200 patients scheduled for laparoscopic hysterectomy by a single operator were compared using learning curves according to operation time, operative blood loss, and occurrence of complications. RESULTS: Learning curves for both types of hysterectomy were rather similiar, but the learning of the laparoscopic procedure seemed to be quicker. With increasing experience the operating time decreased by 25% in abdominal and by 41% in laparoscopic hysterectomies. The mean operating time in abdominal hysterectomy was 74 min and 70 min in laparoscopic hysterectomy. Operative blood loss decreased by 50% and 44%, respectively. The mean operative blood loss was smaller (203 vs 295 ml, p<0.0001) in laparoscopic hysterectomy. Increased experience had no effect on complication rates in abdominal hysterectomies, but a decrease of 44% was seen in laparoscopic hysterectomies (p<0.05). The overall complication rate (26% vs 22%) were similar for the two techniques, and only a few patients (1.5% vs 1%) had major (bladder or ureteric) complications. CONCLUSIONS: A trained gynecologist can learn the laparoscopic technique for hysterectomy at least as quickly as the abdominal technique.

Aged↗
PubMed2003

Learning curve of a new hospital laboratory. The monitoring of computer-generated turnaround time of laboratory tests in an emergency department.

Learning curves have been described for different health technologies, mainly new surgical or diagnostic procedures, but learning curves for a new hospital's laboratory procedures have not been systematically studied. To monitor the timeliness (turnaround time) of stat tests from the Emergency Department as a marker of laboratory quality and to address the issue of a learning curve for procedures performed in a new hospital laboratory, we employed a computerized system for collecting data of turnaround time (from order entry to result verification) on stat tests from the Emergency Department of a newly opened (July 24, 2000) 471-bed general hospital. The data collection operates without user intervention. We evaluated the turnaround times of stat complete blood count and biochemistry tests from August 2000 to December 2001. Results show that it took 6 to 12 months before the turnaround times reached a plateau, we believe that this is the learning curve of a new hospital laboratory. Computer-generated turnaround times for Emergency Department stat tests appear to be a useful tool for monitoring the quality of laboratory tests and can demonstrate the learning curve of a new hospital laboratory.

Clinical Laboratory Information Systems↗
PubMedDate not supplied

[Ross procedure - how to minimize the effects of learning curve].

The introduction of new procedures in surgery usually implies the costs of the so called learning curve. However patients should not suffer the negative effects of surgeon's learning curves. We report our results with the first 15 Ross procedures, a single surgeon and institution experience, and how it was possible to build a safe learning curve without major consequences for the patients. We emphasize the need for a continuous program of surgical performance assessment throughout the learning curve period, as was demonstrated in our series.

Adolescent↗
PubMedDate not supplied

The sales learning curve.

When a company launches a new product into a new market, the temptation is to immediately ramp up sales force capacity to gain customers as quickly as possible. But hiring a full sales force too early just causes the firm to burn through cash and fail to meet revenue expectations. Before it can sell an innovative product efficiently, the entire organization needs to learn how customers will acquire and use it, a process the authors call the sales learning curve. The concept of a learning curve is well understood in manufacturing. Employees transfer knowledge and experience back and forth between the production line and purchasing, manufacturing, engineering, planning, and operations. The sales learning curve unfolds similarly through the give-and-take between the company--marketing, sales, product support, and product development--and its customers. As customers adopt the product, the firm modifies both the offering and the processes associated with making and selling it. Progress along the manufacturing curve is measured by tracking cost per unit: The more a firm learns about the manufacturing process, the more efficient it becomes, and the lower the unit cost goes. Progress along the sales learning curve is measured in an analogous way: The more a company learns about the sales process, the more efficient it becomes at selling, and the higher the sales yield. As the sales yield increases, the sales learning process unfolds in three distinct phases--initiation, transition, and execution. Each phase requires a different size--and kind--of sales force and represents a different stage in a company's production, marketing, and sales strategies. Adjusting those strategies as the firm progresses along the sales learning curve allows managers to plan resource allocation more accurately, set appropriate expectations, avoid disastrous cash shortfalls, and reduce both the time and money required to turn a profit.

Commerce↗
PubMed1998

Learning curve characteristics of pacing lead extraction with a laser sheath.

The learning curve characteristics of lead extraction with a laser sheath were examined in 19 patients. Forty-two leads were removed: five leads were removed by traction alone, five required a femoral approach as a primary procedure and a laser sheath was used in 32 lead extraction attempts. Primary laser success was achieved in 26 attempts (81%). A femoral approach was successfully applied as a back-up procedure in five of the failures. Overall, 26% of the leads were removed by the femoral approach. The overall success rate was 98% (41 of 42 leads). No variables related to the patients, leads, or extraction techniques were significantly related to failure of laser sheath extraction. There was a distinct learning curve with all but one failure occurring in the first half of our cases. All failures occurred with leads implanted from the right subclavian vein. In four, a sharply angled curve at the subclavian vein-superior vena cava junction could not be passed with the laser sheath. The ability to smooth this curve improved the results during the learning curve. All procedures were performed in the operating room for safety reasons. This precaution was lifesaving in a case of acute tamponade after laser extraction of an atrial lead. In another case the left internal mammary artery was torn after laser sheath extraction, causing the formation of a false aneurysm. New pacing leads were introduced in nine patients during the same procedure. The mean procedure time was 255 +/- 110 min. reflecting the complexity of these procedures.

Clinical Competence↗