Best Evidence Topics

Case-control checklist (including harm)

Kostis et al
Weekend versus Weekday Admission and Mortality from Myocardial Infarction
New England Journal of Medicine
March 15, 2007; 1099-1109
  • Submitted by:Tom Leckie - SpR A+E
  • Institution:Hope Hospital
  • Date submitted:20th March 2007
Before CA, i rated this paper: 7/10
1 Objectives and hypotheses
1.1 Are the objectives of the study clearly stated?
  Yes - to Compare mortality rates weekday/weekend and to see if differences in intervention explain any differences in Mortality found
2 Design
2.1 Is the study design suitable for the objectives?
2.2 Who / what was studied?
  Myocardial infarction Data Acquisition System (MIDAS) - Non Federal Acute care hospitals in New Jersey. Patients with their first admission with the diagnosis of MI as the primary reason between 1987 and 2002
2.3 Was this the right sample to answer the objectives?
2.4 Did this include a clearly identified comparison group, identical in all aspects other than the exposure?
  Admission on Weekdays Vs admission on Saturday or Sunday
2.5 Did the exposure precede outcome?
2.6 Is the study large enough to achieve its objectives? Have sample size estimates been performed?
  No sample size calculation performed
2.7 Were all subjects accounted for?
  No but given that the payment of the hospital is dependent on accurate coding there are unlikely to be many missing
2.8 Were all appropriate outcomes considered?
2.9 Has ethical approval been obtained if appropriate?
  No mention made
3 Measurement and observation
3.1 Is it clear what was measured, how it was measured and what the outcomes were?
  Yes - Mortality 1-7,14,21,30,180 and 365 days.
Catheterisation, PCI and CABG ,days to procedure for 1-7 days and up to 30 days
3.2 Were the exposures to the agent and outcomes measured in the same way in all of the groups compared?
3.3 Were the assessments of exposure blinded to outcome?
  Yes - Automated proceedure and the operator was blinded as to the day of admission
3.4 Was follow up sufficiently long and complete?
  Automated record linkage software with New Jersey Death registration files. Subgroup analysis using only new Jersy residents and only patients from hospitals with PCI.
3.5 Are the measurements valid?
3.6 Are the measurements reliable?
3.7 Are the measurements reproducible?
4 Presentation of results
4.1 Are the basic data adequately described?
  Yes - Table 1
4.2 Are the results presented clearly, objectively and in sufficient detail to enable readers to make their own judgement?
  Banded for year of admission.
Coronay intervention Table 2
Mortality Table 3
4.3 Can you construct a 2x2 table of exposure and outcome?
  30 day mortality x exposure to weekend!
4.4 Was there a dose response effect?
4.5 Are the results internally consistent, i.e. do the numbers add up properly?
  Most of the discussion surrounds the 1999 to 2002 data set and adds up I cannot get all deaths at 30 days to be significant even though they say it is.
5 Analysis
5.1 Are the data suitable for analysis?
5.2 Are the methods appropriate to the data?
5.3 Are any statistics correctly performed and interpreted?
5.4 Are relative risks or odds presented with confidence intervals?
  Hazard Ratios with confidence intervals
6 Discussion
6.1 Are the results discussed in relation to existing knowledge on the subject and study objectives?
6.2 Is a causal relationship between exposure and outcome suggested?
6.3 If so, is this causal relationship justified?
6.4 Is the discussion biased?
7 Interpretation
7.1 Are the author's conclusions justified by the data?
7.2 What level of evidence has this paper presented? (using CEBM levels)
7.3 Does this paper help me answer my problem?
  It suggests that the 9-5 Monday to Friday Hospital is not good for patients with acute MI. It provides an argument for extending PCI to weekends.
After CA, i rated this paper: 8/10
8 Implementation
8.1 Can any necessary change be implemented in practice?
8.2 What aids to implementation exist?
  Already have PCI available during working hours for some patients
8.3 What barriers to implementation exist?
  Financial and logistical difficulties in the UK much worse.