Introducing a methodology for estimating duration of surgery in health services research

doi:10.1016/j.jclinepi.2007.10.015

Journal of Clinical Epidemiology

Volume 61, Issue 9, September 2008, Pages 882-889

https://doi.org/10.1016/j.jclinepi.2007.10.015 Get rights and content

Abstract

Objectives

The duration of surgery is an indicator for the quality, risks, and efficiency of surgical procedures. We introduce a new methodology for assessing the duration of surgery based on anesthesiology billing records, along with reviewing its fundamental logic and limitations.

Study Design and Setting

The validity of the methodology was assessed through a population-based cohort of patients (n = 480,986) undergoing elective operations in 246 Ontario hospitals with 1,084 anesthesiologists between April 1, 1992 and March 31, 2002 (10 years).

Results

The weaknesses of the methodology relate to missing data, self-serving exaggerations by providers, imprecisions from clinical diversity, upper limits due to accounting regulations, fluctuations from updates over the years, national differences in reimbursement schedules, and the general failings of claims base analyses. The strengths of the methodology are in providing data that match clinical experiences, correspond to chart review, are consistent over time, can detect differences where differences would be anticipated, and might have implications for examining patient outcomes after long surgical times.

Conclusions

We suggest that an understanding and application of large studies of surgical duration may help scientists explore selected questions concerning postoperative complications.

Introduction

The duration of an operation has clinical, economic, and theoretic implications for modern medical care. It is important for patients when gauging the extent of surgery and predicting their foreseeable speed of recovery. The anticipated duration of surgery is crucial for providers for scheduling operations and for organizing a complicated health-care system [1]. The actual duration of surgery also gives direct insights regarding the net combination of procedure difficulty, patient complexity, and surgeon skill [2]. Moreover, duration varies widely from less than 15 minutes for a bladder cystoscopy to more than 15 hours for conjoint twin separation.

Analyzing surgery duration is easy if intraoperative observation is feasible or if providers are compelled to report times directly [3]. More commonly, the duration of surgery is assessed retrospectively from intraoperative records. The classic way in hospitals, for example, is to consult the anesthesiology sheet because patients can rarely report this aspect of their care for themselves. The anesthesiology sheet typically provides a profile of the operation in 15-minute increments with the start time and end time explicitly documented. Interviewing surgeons is another way to estimate surgery duration in clinical practice, although somewhat prone to reporting bias [4].

We are aware of few efforts to develop computerized health services research methods for estimating surgery duration. The usual approach is chart review methodology such as is popular in infectious disease surveillance studies; however, such methods are laborious or focus on volunteer samples [5], [6]. Herein, we develop a new methodology for tackling this challenge. We apply our methodology to studying a cohort of patients undergoing surgery in Ontario. The goal is to offer a quantitative method for studying large numbers of patients. We also provide descriptive results on reliability and validity after applying our methods to real-world data.

Section snippets

Setting

Ontario is the largest province of Canada accounting for about one-third of the country's total population. Anesthesiologists in Ontario are generally paid fee for service when managing a patient during surgery. Such anesthesiology bills are submitted centrally to a single payer, the Ministry of Health, through the Ontario Hospital Insurance Program (OHIP). Proven cases of fraud are rare, although some over billing and missed billing are inevitable in any payment system [7]. OHIP bills are

Patient case

Consider the following hypothetical case to illustrate anesthesiology billing. A 25-year-old man undergoes an uncomplicated appendectomy on Saturday afternoon in 1992 with a surgical time of 2 hours and 9 minutes. The OHIP schedule in that year identifies a set-up fee of five service units, a premium of 50% due to weekend work, and no other special fees. In this case, the duration service units are computed as four for the first hour, eight for the next hour, and two for the remaining 9 minutes

Missing data

The first failing in our methodology for estimating surgery duration relates to missing data. For example, when we analyzed 480,986 elective operations from April 1, 1992 to March 31, 2002 we found no anesthesiology bills in 98,194 cases (20%). This attrition occurs because some procedures do not require an anesthesiologist (e.g., colonoscopy), anesthesia is sometimes provided by clinicians who do not bill OHIP (e.g., those on alternative payment plans or nurse practitioners), and some bills

Sensibility

We identified the 50 most frequent elective surgeries (n > 1,000 for each procedure) conducted between April 1, 1992 and March 31, 2002 (10 years) to obtain pilot results using the methodology. For each operation, we calculated the distribution of surgical durations (Table 1). Overall, we found the method yielded plausible values for the mean and median times of each procedure, along with impressive levels of variation in some cases. The general pattern of results from the method seemed to match

Summary

Estimates of surgical duration are rare in health services research and not previously available in Canada to our knowledge. Most literature on surgical duration, instead, reflects clinical surveillance in the United States and the United Kingdom with limited power, crude statistical models, or selection bias [13], [15], [16], [17]. Herein, we introduce a method that is feasible, rigorous, novel, ethical, and reasonable. We also provide technical details about the method, list the main

Acknowledgments

This work was supported by the Canada Research Chair in Medical Decision Sciences, the Canadian Institutes of Health Research, the National Institutes of Health Resuscitation Outcomes Consortium, the Clinician Scientist Training Program of the University of Toronto, and the PSI Foundation of Ontario. All authors have participated in the study design, interpretation of results, and approval of the final draft. Donald Redelmeier had full access to all the data, final authority for the decision to

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Resident Trainees Increase Surgical Time: A Comparison of Obstetric and Gynaecologic Procedures in Academic Versus Community Hospitals
2020, Journal of Obstetrics and Gynaecology Canada
Citation Excerpt :
Surgical training for obstetrics and gynaecology residents in Ontario primarily occurs in one of six medical schools, comprising 19 hospitals. The outcome variable of surgical duration was captured using anaesthetic billing records according to the methods described by Redelmeier et al.9 Patient complexity was measured using the Johns Hopkins University Adjusted Clinical Group case-mix system's Resource Utilization Bands (RUB)10 and was based on care received in the 18 months before surgery. All analysis was performed using SAS software version 9.3 (SAS Institute, Cary, NC).
The impact of resident involvement in the operating room for common procedures in obstetrics and gynaecology can shed light on the resource demands of teaching. The objective of this study was to quantify the increased surgical time associated with teaching obstetrics and gynaecology resident trainees across a range of procedures known to require surgical assistance.
This population-based retrospective cohort study compared surgical duration between academic (teaching) hospitals and community (non-teaching) hospitals. The cohort was made up of adult residents of Ontario between fiscal years 2002 and 2013 who were undergoing commonly performed obstetrics and gynaecologic procedures. The most commonly billed procedures requiring surgical assistance were included: cesarean section, anterior or posterior repair, anterior and posterior repair, salpingo-oophorectomy, myomectomy, ectopic pregnancy, total or subtotal hysterectomy, vaginal hysterectomy, and laparoscopic hysterectomy. Linked administrative databases held at the Institute of Clinical Evaluative Sciences (ICES) were used to define patient-, surgeon-, institution-, and procedure-related variables to limit confounding. Surgical duration, determined by anaesthetic billing records, was analyzed using a negative binomial regression.
The total cohort included 337 389 surgical procedures. Of these procedures, 28% (94 203 procedures) were conducted in academic settings. The mean surgical duration of the procedures of interest (excluding vaginal hysterectomy) was significantly longer in academic hospitals compared with community hospitals. With many controls for case variability, this time differential reflects the burden of teaching resident trainees and other learners in the academic environment. The operating time increased between 6% and 20% for cases completed in academic centres versus in the community. As an example, the mean surgical duration of cesarean sections was 20.6 minutes (19%) longer in academic centres. Furthermore, the data highlighted a trend of increased teaching time for laparoscopic procedures compared with open procedures. The time ratio was the greatest for salpingo-oophortectomy and surgical management of ectopic pregnancies. The additional cost of carrying out these nine procedures in academic centres during the study period was $16.3 million.
The cost of teaching resident trainees is increased operative time. This increased surgical cost in a publicly funded system must be considered as funding models evolve.
L'importance de la participation des résidents en salle d'opération lors d'interventions obstétricales ou gynécologiques courantes peut mettre en lumière les besoins en ressources pour l'enseignement. L'objectif de cette étude était de quantifier l'augmentation de la durée des interventions chirurgicales liée à la formation des résidents en obstétrique et gynécologie pour toute une gamme d'interventions qui requièrent une assistance chirurgicale.
Cette étude de cohorte rétrospective sur une population a comparé la durée des interventions chirurgicales dans les hôpitaux universitaires (où un enseignement est offert) et les hôpitaux communautaires (aucun enseignement offert). La cohorte se composait d'Ontariennes d'âge adulte qui, entre les exercices financiers 2002 et 2013, ont subi des interventions gynécologiques ou obstétricales courantes. Les interventions requérant une assistance chirurgicale les plus couramment facturées étaient comprises dans l'étude : césarienne, réparation antérieure ou postérieure, salpingo-ovariectomie, myomectomie, grossesse extra-utérine, hystérectomie totale ou subtotale, hystérectomie vaginale et hystérectomie laparoscopique. Des bases de données administratives couplées tenues par l'Institute of Clinical Evaluative Sciences (ICES) ont été utilisées pour déterminer les variables liées aux patientes, aux chirurgiens, aux établissements et aux interventions pour limiter le facteur de confusion. La durée des interventions, déterminée par les dossiers de facturation d'anesthésie, a été analysée par régression binomiale négative.
L'ensemble de la cohorte comportait 337 389 interventions chirurgicales. Parmi ces interventions, 28 % (94 203) ont été réalisées dans un contexte d'enseignement. La durée moyenne des interventions chirurgicales d'intérêt (à l'exception des hystérectomies vaginales) était considérablement plus longue dans les hôpitaux universitaires que dans les hôpitaux communautaires. En raison des critères de variabilité des cas, cette différence de durée témoigne du fardeau de l'enseignement aux résidents et autres apprentis dans un milieu universitaire. Le temps opératoire était de 6 % à 20 % plus élevé pour les interventions réalisées en centre hospitalier universitaire par rapport à celles en hôpital communautaire. Par exemple, la durée moyenne des césariennes durait 20,6 minutes (19 %) de plus dans les hôpitaux universitaires. De plus, les données font état d'une tendance à la hausse du temps d'enseignement pour les interventions laparoscopiques par rapport aux interventions à ciel ouvert. La salpingo-ovariectomie et la prise en charge chirurgicale des grossesses extra-utérines présentaient l'écart le plus important entre les hôpitaux universitaires et communautaires. Les coûts supplémentaires liés à la pratique de ces neuf interventions dans les hôpitaux universitaires au cours de la période visée par l'étude s'élevaient à 16,3 millions de dollars.
L'enseignement aux résidents se traduit par une augmentation du temps opératoire. Il y a lieu de tenir compte de cette augmentation du coût chirurgical au sein d'un système financé par l'État à mesure qu'évoluent les modèles de financement.
Surgical duration is associated with an increased risk of periprosthetic infection following total knee arthroplasty: A population-based retrospective cohort study
2019, EClinicalMedicine
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Foremost, surgical duration was defined based on operating room entry and exit times. The data on surgery times has high face validity – basic tests of their quality included that 1) start times always occurred after the hospital admission time and that 2) “sensible” surgical durations are predicted by surgery start and end times [13]. However, the surgical duration we utilize in this study does not solely include the time from incision to closure, but also captures time required positioning the patient and inducing anesthesia.
Total knee arthroplasty (TKA) is one the most common elective procedures in the world. Post-operative infection is one of its most devastating complications, often necessitating multiple additional surgeries. We aimed to describe the relationship between surgical duration and risk of deep infection following primary elective TKA.
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In a cohort of TKA recipients, we found that procedure lengths longer than 100 min were associated with a significantly increased risk of deep infection requiring surgery. This time threshold serves a useful time-point to identify patients that require closer surveillance.
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As per standard definitions, these events included any infection of the surgical incision or surgically manipulated structures that developed within 30 days of the procedure.20 From the hospital discharge database we abstracted procedure risk factors, including year of procedure, exact procedure code, implantation of prosthetic material, and procedure duration (Table I).21 Patient risk factors were abstracted from records for the three years prior to the surgical procedure, including demographic details, markers of healthcare utilisation, and comorbidities (Table II).
In this population-based retrospective cohort study, we examined the frequency, severity, and prediction of post-discharge surgical site infections (SSIs). We evaluated all patients admitted for their first elective surgical procedure in Ontario, Canada, between 1 April 2002 and 31 March 2008. Procedure and patient characteristics were derived from linked hospital, emergency room and physician claims databases within Canada's universal healthcare system. The 30 day risk of SSI was derived from the initial hospital admission, outpatient consultations, return emergency room visits and readmissions. The cohort included 622 683 patients, of whom 84 081 (13.5%) were diagnosed with SSI, and more than half (48 725) were diagnosed post-discharge. Post-discharge infections were associated with an increased risk of reoperation (odds ratio: 2.28; 95% confidence interval: 2.11–2.48), return emergency room visit (9.08; 8.89–9.27), and readmission (6.16; 5.98–6.35). The most common risk index predicted incremental increases in the risk of in-hospital SSI, but did not predict increases in the risk of post-discharge infection. Patients with post-discharge infections had baseline characteristics more akin to uninfected patients than patients with in-hospital infections. Predictors of post-discharge infection included shorter procedure duration, shorter length of stay, rural residence, alcoholism, diabetes and obesity. Post-discharge SSIs are frequent, severe, scattered over time and location, and hard to predict using common risk indices. They represent an important hidden burden in our healthcare system.
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Reporting and evaluating wait times for urgent hip fracture surgery in Ontario, Canada
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An advantage of these Canadian data compared with data from the United States is the ability to capture exact wait times in hours (versus days) and the time elapsed in transfer between hospitals.48,58 Other potential applications of these data include more accurately identifying after-hours surgery, 19 durations of surgery59 and overlapping surgical procedures.1,60,61 Although specific reasons for delay could not be assessed in the data that were sampled, risk-adjusted differences observed between hospitals should not reflect clinical reasons, but rather processes of care at different hospitals.
Although a delay of 24 hours for hip fracture repair is associated with medical complications and costs, it is unknown how long patients wait for surgery for hip fracture. We describe novel methods for measuring exact urgent and emergent surgical wait times (in hours) and the factors that influence them.
Adults aged 45 years and older who underwent surgery for hip fracture (the most common urgently performed procedure) in Ontario, Canada, between 2009 and 2014 were eligible. Validated data from linked health administrative databases were used. The primary outcome was the time elapsed from hospital arrival recorded in the National Ambulatory Care Reporting System until the time of surgery recorded in the Discharge Abstract Database (in hours). The influence of patient, physician and hospital factors on wait times was investigated using 3-level, hierarchical linear regression models.
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Teaching surgery takes time: The impact of surgical education on time in the operating room
2016, Canadian Journal of Surgery
It is generally accepted that surgical training is associated with increased surgical duration. The purpose of this study was to determine the magnitude of this increase for common surgical procedures by comparing surgery duration in teaching and nonteaching hospitals.
This retrospective population-based cohort study included all adult residents of Ontario, Canada, who underwent 1 of 14 surgical procedures between 2002 and 2012. We used several linked administrative databases to identify the study cohort in addition to patient-, surgeon- and procedure-related variables. We determined surgery duration using anesthesiology billing records. Negative binomial regression was used to model the association between teaching versus nonteaching hospital status and surgery duration.
Of the 713 573 surgical cases included in this study, 20.8% were performed in a teaching hospital. For each procedure, the mean surgery duration was significantly longer for teaching hospitals, with differences ranging from 5 to 62 minutes across individual procedures in unadjusted analyses (all p < 0.001). In regression analysis, procedures performed in teaching hospitals were associated with an overall 22% (95% confidence interval 20%–24%) increase in surgery duration, adjusting for patient-, surgeon- and procedure-related variables as well as the clustering of patients within surgeons and hospitals.
Our results show that a wide range of surgical procedures require significantly more time to perform in teaching than nonteaching hospitals. Given the magnitude of this difference, the impact of surgical training on health care costs and clinical outcomes should be a priority for future studies.
Il est généralement admis que la formation chirurgicale est associée à des interventions plus longues. L’objectif de la présente étude était de déterminer l’ampleur de cette augmentation pour les chirurgies courantes en comparant la durée des interventions dans les hôpitaux universitaires et les autres hôpitaux.
Dans le cadre d’une étude de cohorte rétrospective basée sur la population, nous avons recensé tous les résidents adultes de l’Ontario (Canada) qui ont subi une intervention chirurgicale parmi une liste de 14 entre 2002 et 2012. À l’aide de plusieurs bases de données administratives reliées, nous avons constitué la cohorte de l’étude et recueilli des variables associées aux patients, aux chirurgiens et aux interventions. Nous avons déterminé la durée des opérations à partir des dossiers de facturation d’anesthésiologie. Une régression binomiale négative a été utilisée pour modéliser le lien entre le statut des hôpitaux — universitaires ou non — et la durée.
Des 713 573 chirurgies à l’étude, 20,8 % ont eu lieu dans un hôpital universitaire. Dans tous les cas, la durée moyenne était significativement plus longue dans les hôpitaux universitaires, les écarts variant de 5 à 62 minutes pour chaque intervention dans les analyses non corrigées (p < 0,001 dans tous les cas). Selon l’analyse de régression, les chirurgies effectuées dans les hôpitaux universitaires étaient associées à une augmentation globale de la durée de 22 % (intervalle de confiance à 95 %, 20 %–24 %), après ajustement pour les variables liées aux patients, aux chirurgiens et aux interventions ainsi que pour la densité de patients pris en charge par les chirurgiens et les hôpitaux.
Nos résultats montrent que de nombreuses interventions chirurgicales durent considérablement plus longtemps dans les hôpitaux universitaires que dans les autres hôpitaux. Étant donné l’ampleur de cet écart, l’étude de l’incidence de la formation chirurgicale sur les coûts des soins de santé et les résultats cliniques devrait être une priorité pour les recherches futures.

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Original ArticleIntroducing a methodology for estimating duration of surgery in health services research

Abstract

Objectives

Study Design and Setting

Results

Conclusions

Introduction

Section snippets

Setting

Patient case

Missing data

Sensibility

Summary

Acknowledgments

J Am Coll Surg

J Hosp Infect

Lancet

The effects of surgical case duration and type of surgery on hourly clinical productivity of anesthesiologists

Anesth Analg

The effect of the learning curve on the duration and perioperative complications of laparoscopically assisted vaginal hysterectomy

Acta Obstet Gynecol Scand

Estimating anesthesia and surgical procedure times from Medicare anesthesia claims

Anesthesiology

Problems for clinical judgement: 2. Obtaining a reliable past medical history

CMAJ

An analysis of one potential form of health care fraud in Canada

CMAJ

Original Article
Introducing a methodology for estimating duration of surgery in health services research