Geographic Influences on Appendicectomy Outcomes
Introduction
Appendicitis is a common condition which represents a significant resource burden for the Scottish National Health Service (NHS). It is unknown whether there are significant differences in outcomes following appendicectomy which may be explained by geographic factors.
Aims
The aim of this study is to describe appendicectomy outcomes in Scotland as they vary by the urban-rural nature of the patient's home location and travel time from hospital.
Methods
This research study is a retrospective observational enquiry which will utilise administrative data from the Information Services Division (ISD) of NHS National Services Scotland. Patient episodes will be identified by a procedure code for appendicectomy, and the urban-rural classification of patients will be derived from postcode data. Travel time from hospital will also be estimated through postcode data. The investigators will study a 10 year period from January 2001 to December 2010.
Primary outcome measures will be risk-adjusted 30 day/inpatient mortality, 30 day readmission rate, 30 day re-operation rate, length of stay and negative appendicectomy rates.
調査の概要
状態
条件
詳細な説明
The aim of this study is to explore the possibility that outcome from appendicectomy may vary according to:
- the urban-rural nature of the patient's home location and
- travel time from hospital.
This is a retrospective study of all appendicectomies performed in Scotland during the period from 1st January 2001 - 31st December 2010. It will use routinely collected administrative data from the Information Services Division (ISD) of NHS National Services Scotland.
Potentially significant confounding variables such as age, gender, and co-morbidity will be studied for their predictive value in a univariate model and included in a multivariate model if they remain significant.
There is no single appendicectomy outcome measure which is a literature standard, so all of the following will be evaluated as primary outcome measures: risk-adjusted 30 day/inpatient mortality, 30 day readmission rate, 30 day re-operation rate, length of stay and negative appendicectomy rates.
The registry which will supply the data for this study is the Scottish Morbidity Record 01 (SMR01), the full title of which is the "General / Acute Inpatient and Day Case dataset" (see http://www.adls.ac.uk/nhs-scotland/general-acute-inpatient-day-case-smr01/?detail). SMR01 is collated and administered by ISD, and data submission is mandatory for all Scottish NHS providers of in-patient or day-case care. Approximately 1.4 million records are added each year. Diagnoses are coded according to International Classification of Diseases (ICD)-10 standards and procedures are coded according to the United Kingdom's Office of Population Census Statistics (OPCS) standards, the most recent of which is version 4.5.
The data quality in SMR01 is high and is assured by regular internal audits. In the 2010 audit of accuracy, Main Condition was recorded with an accuracy of 88% and Main Procedure was recorded with an accuracy of 94%. Where data inconsistencies are identified in the extract supplied for this study, further clarification will be obtained where possible with ISD's data retrieval support team. Data completeness is very high in SMR01. However, where significant volumes of data are missing or unusable, the need for data imputation will be explored.
The study period was decided on pragmatically by a desire to provide an assessment of current practice, fully within the era of widely practised laparoscopic surgery. A power calculation also suggested that this would provide an adequate sample size to demonstrate differences.
Our power calculation- specific to length of stay- was based on Faiz O, Clark J, Brown T, Bottle A, Antoniou A, Farrands P, et al. Traditional and Laparoscopic Appendectomy in Adults. Ann Surg. 2008 Nov;248(5):800-6. In their cohort of 259,735 appendicectomies performed from 1996-2006, the geometric mean length of stay was 3.52, with SD 1.8. We decided that a difference of 0.5 days would be 'clinically significant'. We specified alpha 0.05 and Power 0.9, and an allocation ratio of 2 (allowing comparison of one tertile to two others). A two-sided t-test of difference between two independent means was performed in G*Power 3.1.7. This demonstrated that a total N of 616 was required to demonstrate this difference. According to ISD figures, there were 3,712 appendicectomy procedures performed in 2010/11, so with numbers available we will be able to detect a clinically significant difference in length of stay.
The investigators will use the Scottish government's own 8-fold urban-rural classification system (see http://www.scotland.gov.uk/Topics/Statistics/About/Methodology/UrbanRuralClassification) to investigate the possible relationship between patient geographical location and outcome. Urban-rural categories may be grouped for analysis, depending on initial exploratory work.
The investigators will further calculate the approximate travelling time from patient home location (using postcode) to the treating hospital, by constructing isochrones at time/distance intervals from hospitals. Travel time will be evaluated as a continuous and discrete variable.
研究の種類
入学 (予想される)
連絡先と場所
研究場所
-
-
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All Scottish surgical facilities、イギリス
- All Scottish NHS Hospitals
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-
参加基準
適格基準
就学可能な年齢
- 子
- 大人
- 高齢者
健康ボランティアの受け入れ
受講資格のある性別
サンプリング方法
調査対象母集団
説明
Inclusion Criteria:
- All patients, of all ages, undergoing appendicectomy (OPCS code H01) during the time period January 2001 - December 2010.
Exclusion Criteria:
- Patients undergoing appendicectomy for whom this is incidental to a more major abdominal procedure.
- Patients non-resident in Scotland.
研究計画
研究はどのように設計されていますか?
デザインの詳細
コホートと介入
グループ/コホート |
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都市と農村の分類 3: アクセスしやすい小さな町
3,000 人から 10,000 人の集落で、車で 30 分以内に 10,000 人以上の集落があります。
|
都市と農村の分類 4: 僻地の小さな町
3,000 人から 10,000 人の集落で、10,000 人以上の集落までの移動時間が 30 分を超える集落。
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Urban-Rural Classification 1: Large Urban Areas
Settlements of over 125,000 people.
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Urban-Rural Classification 2: Other Urban Areas
Settlements of 10,000 to 125,000 people.
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Urban-Rural Classification 5: Very Remote Small Towns
Settlements of between 3,000 and 10,000 people and with a drive time of over 60 minutes to a settlement of 10,000 or more.
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Urban-Rural Classification 6: Accessible Rural
Areas with a population of less than 3,000 people, and within a 30 minute drive time of a settlement of 10,000 or more.
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Urban-Rural Classification 7: Remote Rural
Areas with a population of less than 3,000 people, and with a drive time of over 30 minutes to a settlement of 10,000 or more.
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Urban-Rural Classification 8: Very Remote Rural
Areas with a population of less than 3,000 people, and with a drive time of over 60 minutes to a settlement of 10,000 or more.
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Travel Time - see below
Travel time will be analysed as both a continuous and discrete variable.
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この研究は何を測定していますか?
主要な結果の測定
結果測定 |
メジャーの説明 |
時間枠 |
---|---|---|
Post-operative length of stay
時間枠:From date of appendicectomy to date of discharge (whole days) - see below
|
(Whole) days from date of laparotomy to date of discharge.
Because this is a retrospective study using a complete national data set, with the last admission 2.5 years distant from the time of data collection, we will use actual time period rather than censoring length of stay at a set point.
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From date of appendicectomy to date of discharge (whole days) - see below
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Re-operation
時間枠:Within the index admission or within 30 days of discharge
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The occurrence of an abdominal procedure either subsequent to appendicectomy and within the index admission, or ≤30 days of discharge.
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Within the index admission or within 30 days of discharge
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再入学
時間枠:初診日から30日以内
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-病院の専門分野への再入院 退院日から30日以内。
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初診日から30日以内
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死亡
時間枠:処置後30日以内、または連続入院中
|
-入院患者としての死亡または30日以内の処置。
死亡は、登録局の死亡データベースにリンクされている SMR01 から認識されます。
|
処置後30日以内、または連続入院中
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Negative Appendicectomy Rate
時間枠:At time of index procedure
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The rate of appendicectomies performed in which the appendix is found to be normal.
This will be detected by the use of ICD-10 codes.
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At time of index procedure
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協力者と研究者
スポンサー
研究記録日
主要日程の研究
研究開始
一次修了 (実際)
研究の完了 (実際)
試験登録日
最初に提出
QC基準を満たした最初の提出物
最初の投稿 (見積もり)
学習記録の更新
投稿された最後の更新 (見積もり)
QC基準を満たした最後の更新が送信されました
最終確認日
詳しくは
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