APPENDIX 1. SEARCH RESULTS FROM FIVE DATABASES IN APRIL 2020
Embase.com 702 692*
Medline Ovid 528 323*
Web of science 232 63*
Cochrane CENTRAL 71 52*
Google Scholar 200 184*
Total: 1733 1223*
*unique, total duplicates removed 510 Embase.com 702
('surgical infection'/de OR 'postoperative infection'/de OR 'postoperative complication'/de/mj OR (('hospital infection'/de OR 'wound infection'/de) AND surgery/de) OR (((surg* OR postoperati* OR operati*) NEAR/6 (infect*)):ab,ti OR ((surgic* OR postoperati* OR operati*) NEAR/3 (complicat* OR adverse)):ti)) AND ('climate'/de OR 'weather'/de OR 'season'/exp OR meteorology/de OR 'meteorological phenomena'/de OR 'air temperature'/de OR (climate OR weather OR meteorolog* OR season* OR ((warm* OR outside OR outdoor* OR air) NEAR/3 temperatur*) OR summer OR autumn OR spring OR winter):ab,ti)
Medline Ovid 528
(Surgical Wound Infection/ OR * Postoperative Complications/ OR ((hospital infection/ OR wound infection/) AND surgery/) OR (((surg* OR postoperati* OR operati*) ADJ6 (infect*)).ab,ti. OR ((surgic*
OR postoperati* OR operati*) ADJ3 (complicat* OR adverse)).ti.)) AND (exp Climate/ OR Weather/ OR Seasons/ OR Meteorology/ OR Meteorological Concepts/ OR (climate OR weather OR meteorolog* OR season* OR ((warm* OR outside OR outdoor* OR air) ADJ3 temperatur*) OR summer OR autumn OR spring OR winter).ab,ti.)
Web of Science 232
((TS=((surg* OR postoperati* OR operati*) NEAR/5 (infect*)) OR TI=((surgic* OR postoperati* OR operati*) NEAR/2 (complicat* OR adverse)))) AND TS=((climate OR weather OR meteorolog* OR season* OR ((warm* OR outside OR outdoor* OR air) NEAR/2 temperatur*) OR summer OR autumn OR spring OR winter))
Cochrane CENTRAL 71
((((surg* OR postoperati* OR operati*) NEAR/6 (infect*)):ab,ti OR ((surgic* OR postoperati* OR operati*) NEAR/3 (complicat* OR adverse)):ti)) AND ((climate OR weather OR meteorolog* OR season* OR ((warm* OR outside OR outdoor* OR air) NEAR/3 temperatur*) OR summer OR autumn OR spring OR winter):ab,ti)
Google Scholar 200
"surgical|postoperative|operative infections"
climate|weather|meteorological|seasons|summer|autumn|spring|winter
APPENDIX 2. PRISMA 2009 CHECKLIST
Section/topic # Checklist item Reported on page #
TITLE
Title 1 Identify the report as a systematic review, meta-analysis, or both.
In the title page
ABSTRACT
Structured summary 2 Provide a structured summary including, as applicable: background; objectives; data sources; study eligibility criteria, participants, and interventions; study appraisal and synthesis methods; results;
limitations; conclusions and implications of key findings.
Abstract.docx
INTRODUCTION
Rationale 3 Describe the rationale for the review in the context of what is already known.
Pages 1-2
Objectives 4 Provide an explicit statement of questions being addressed with reference to participants, interventions, comparisons, outcomes, and study design (PICOS).
Pages 1-2, Appendix 3
METHODS
Protocol and
registration
5 Indicate if a review protocol exists, if and where it can be accessed (e.g., Web
n.a.
address), and, if available, provide registration information including registration number.
Eligibility criteria 6 Specify study characteristics (e.g., PICOS, length of follow-up) and report characteristics (e.g., years considered, language, publication status) used as criteria for eligibility, giving rationale.
Pages 3-5, Table 1, Appendix 3
Information sources 7 Describe all information sources (e.g., databases with dates of coverage, contact with study authors to identify additional studies) in the search and date last searched.
Pages 3-5, 6-10, Appendix 1
Search 8 Present full electronic search strategy for at least one database, including any limits used, such that it could be repeated.
Appendix 1
Study selection 9 State the process for selecting studies (i.e., screening, eligibility, included in systematic review, and, if applicable, included in the meta-analysis).
Pages 3-5, Table 1, Figure 1
Data collection process
10 Describe method of data extraction from reports (e.g., piloted forms, independently, in duplicate) and any processes for obtaining and confirming data from investigators.
Pages 3-5, Appendix 4
Data items 11 List and define all variables for which data were sought (e.g., PICOS, funding sources) and any assumptions and simplifications made.
Appendix 4
Risk of bias in individual studies
12 Describe methods used for assessing risk of bias of individual studies (including specification of whether this was done at the study or outcome level), and how this information is to be used in any data synthesis.
Pages 3-5, Table 2
Summary measures 13 State the principal summary measures (e.g., risk ratio, difference in means).
Appendix 4
Synthesis of results 14 Describe the methods of handling data and combining results of studies, if done, including measures of consistency (e.g., I2) for each meta-analysis.
Pages 6-10
Risk of bias across studies
15 Specify any assessment of risk of bias that may affect the cumulative evidence (e.g., publication bias, selective reporting within studies).
Appendix 5, Table 2
Additional analyses 16 Describe methods of additional analyses (e.g., sensitivity or subgroup analyses, meta- regression), if done, indicating which were pre-specified.
Pages 3-5
RESULTS
Study selection 17 Give numbers of studies screened, assessed for eligibility, and included in the review, with reasons for exclusions at each stage, ideally with a flow diagram.
Figure 1
Study characteristics 18 For each study, present characteristics for which data were extracted (e.g., study size, PICOS, follow-up period) and provide the citations.
Pages 6-10, Table 2
Risk of bias within studies
19 Present data on risk of bias of each study and, if available, any outcome level assessment (see item 12).
Table 2
Results of individual studies
20 For all outcomes considered (benefits or harms), present, for each study: (a) simple summary data for each intervention group (b) effect estimates and confidence intervals, ideally with a forest plot.
Pages 6-10, Table 2
Synthesis of results 21 Present results of each meta-analysis done, including confidence intervals and measures of consistency.
Pages 6-8, Figure 2
Risk of bias across studies
22 Present results of any assessment of risk of bias across studies (see Item 15).
Appendix 5
Additional analysis 23 Give results of additional analyses, if done (e.g., sensitivity or subgroup analyses, meta- regression [see Item 16]).
Pages 6-10, Figures 3- 4
DISCUSSION
Summary of evidence 24 Summarize the main findings including the strength of evidence for each main outcome; consider their relevance to key groups (e.g., health-care providers, users, and policy makers).
Pages 11-16
Limitations 25 Discuss limitations at study and outcome level (e.g., risk of bias), and at review level (e.g., incomplete retrieval of identified research, reporting bias).
Pages 11-16
Conclusions 26 Provide a general interpretation of the results in the context of other evidence, and implications for future research.
Page 17
FUNDING
Funding 27 Describe sources of funding for the systematic review and other support (e.g., supply of data); role of funders for the systematic review.
Page 18
From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097.
doi:10.1371/journal.pmed1000097
APPENDIX 3. PICOS
Patient (Problem) Patients undergoing different types of surgical procedures
Intervention (Exposure) Surgery during the warmest period of the year Comparison (Exposure) Surgery during the colder period of the year
Outcomes Incidence of surgical site infections (SSIs)
Study Design Type At least level 5 by Jovell and Navarro-Rubio
APPENDIX 4. VARIABLES OF INTEREST AND DATA EXTRACTION
Included in meta- analysis
Type of surgical procedure
Total amount of surgical procedures
Surgical site infections (SSIs)
OR SSIs (warmest vs coldest period of the year)
OR SSIs (warmest period vs remainder of the year)
OR/ PRR per type of microbial pathogen cultured from SSIs (warmest vs coldest period of the year)
Malik et
al. (2018) X X X X X
Huntley et al.
(2018)
X X X X X
Anthony et al.
(2018)
X X X X X-
Parkinson et al.
(2018)
X X X X X-
Rosas et
al. (2017) X X X X X
Ng et al.
(2017) X X X
Kane et
al. (2014) X X X
Gu et al.
(2018) X X X X X-
Ohya et
al. (2017) X X X X X-
Durkin et
al. (2015) X X X X X X
Gruskay et al.
(2013)
X X X X X
Fortaleza et al.
(2019)
X X
Anthony et al.
(2017)
X X X X-
Durkin et
al. (2015) X X X X X
Nwankwo et al.
(2014)
X X
Duscher et al.
(2018)
X X X X X
Ng et al.
(2014) X X X
Gross et
al. (2017) X X X X
Turan et
al. (2015) X X X X X-
Li et al.
(2004) X X X X X-
APPENDIX 5. BIAS ASSESSMENT USING THE NEWCASTLE-OTTOWA SCALE (NOS) FOR ASSESSING THE QUALITY OF NONRANDOMIZED STUDIES IN META-ANALYSES
Author (year)
Selection (of cohorts) (1pt per item)
Comparability (of cohorts) (max. 2pt)
Assessment of Outcome (1pt per item)
Total Quali ty Score Representativ
eness of the exposed cohort
Selecti on of the non expose d cohort
Ascertainm ent of exposure
Demonstra tion that outcome of interest was not present at start of study
Comparab ility of cohorts on the basis of the design or analysis
Assessm ent of outcome
Long enough follow up for outco mes to occur
Adequ acy of follow up of cohorts
Malik et al.
(2018)
X X X X X X X X 8
Huntle y et al.
(2018)
X X X X X X X X 8
Anthon y et al.
(2018)
X X X X X X X X 8
Parkins on et al.
(2018)
X X X X X X X X 8
Rosas et al.
(2017)
X X X X X X X X 8
Ng et al.
(2017)
X X X X X X X 7
Kane et al.
(2014)
X X X X X X X 7
Gu et al.
(2018)
X X X X X X X X 8
Ohya et al.
(2017)
X X X X X X X X 8
Durkin et al.
(2015)
X X X X XX X X X 9
Gruska y et al.
(2013)
X X X X X X X X 8
Fortale za et al.
(2019)
X X X X X X X 7
Anthon y et al.
(2017)
X X X X X X X X 8
Durkin et al.
(2015)
X X X X XX X X X 9
Nwank wo et al.
(2014)
X X X X X X X 7
Dusche r et al.
(2018)
X X X X X X X X 8
Ng et al.
(2014)
X X X X X X X 7
Gross et al.
(2017)
X X X X X X X X 8
Turan et al.
(2015)
X X X X X X X X 8
Li et al.
(2004)
X X X X X X X X 8
