Systematic review design
Based on the clinical question: “Does physical factors e.g., temperature, humidity and altitude affect the analytical quality of Point of Care testing of blood glucose and does it affect the glycaemic control in individuals with diabetes?”, a search strategy is developed for EMBASE and translated for each database to incorporate relevant participants, interventions, comparators, and outcomes (PICO) [see Additional file 1]. Studies published in English, Danish, Norwegian, Swedish and German are eligible for review. Systematic review and subsequent analysis will be conducted following methods outlined in the PRISMA 2020 statement (5). A populated PRISMA-P checklist is provided [see Additional file 2] (6)
Information sources and search strategy
The following clinical electronic databases with noted limits on dates will be used to identify relevant literature using a systematic search strategy [see Additional file 1]:
EMBASE (2000 - present)
PubMed (2000 - present)
CINAHL (2000 -present)
Academic Search Premier (2000 – present)
SweMed+ (2000-2020)
DANS Easy -former OpenGrey (2000-present)
Cochrane Library (2000 - present)
The technological development of devices measuring blood glucose implies that it is not relevant to use literature published before 2000
To ensure literature saturation, the reference lists of included studies or relevant reviews identified through the search will be scanned for eligible studies.
Population/participants included or excluded in search
Studies on blood glucose test systems with no limit in country and both in-hospital and non-hospital settings are included. Studies conducted in laboratories simulating physical settings or studies using Quality control samples or artificial sample material will be included. Observational studies will also be included.
Participant using Continuous glucose monitoring systems (CSGMS) are not included in the study.
Animal studies are excluded.
Interventions
A broad range of blood glucose meters and matching test strips exposed to varying environmental conditions e.g., high/low temperature, humidity, or altitude. The interventions will be conditions that do not comply with the conditions approved by the manufacturers or conditions which are not within the testing scope of the manufacturer.
Data management
Zotero (7) will be used as the bibliographic management software. All found titles will be stored, duplicates will be removed, and all discarded references will be stored in a Zotero Archive.
Selection process
To achieve a high degree of consistency in the selection process both authors will discuss and adjust the common understanding of inclusion and exclusion criteria by screening the first 100 titles. Both authors will screen the following titles and in case of disagreement, the study will be included for screening by abstract. After screening of all titles, the procedure will be repeated for screening and reading of abstracts. The degree of agreement between authors will be quantified and reported in percentages. Full text of papers selected by abstract will be assessed according to in- and exclusions criteria.
Data collection process and data items
A specifically developed data extraction form will be used for studies found relevant to the selection criteria. Information will include as a minimum:
General details: Title, Authors, reference/source/year of publication, country, setting, study design, sources of funding/competing interest.
Eligibility criteria: POCT brand, analytical method, number of tests performed, intervention type (humidity, altitude, temperature)
Results: duration of testing period, sample size for each intervention type, Standard deviation, percent coefficient of variation (CV%) and discrepancy
Main Outcomes
The following outcomes are evaluated:
Estimation of precision under varying environmental condition compared to precision recommended by manufacturer or clinical guideline.
Estimation of accuracy under varying environmental conditions compared to accuracy recommended by manufacturer or clinical guideline.
The clinical impact of the estimated precision and accuracy will be assessed.
Risk of bias
Since the review question is focused on the analytical quality of glucose meters exposed to different physical factors, the selection of patient groups is not relevant. The risk of bias will be evaluated by choosing an appropriate tool from acknowledged institutions i.e. Joanna Briggs Critical Appraisal for Systematic Reviews Checklist tools or the Critical Appraisal Skills Programme (CASP).(8)
Data analysis and synthesis of evidence
Data will be presented in different types of ranked summary tables for each environmental condition evaluated. A performance summary table will be presented for each type of Glucometer included in the study. Homogenous results will be pooled and summarized statistically for meta-analysis. Narrative synthesis will be performed for heterogeneous data that cannot be pooled for meta-analysis. Reporting will follow the Preferred Items for Systematic Reviews and Meta-Analysis 2020 (PRISMA 2020). (5)
Meta-Bias
Histograms may be used to visualize and investigate the distribution of studies containing simulation of physical settings versus experiments in actual physical settings. Histograms may also be used to show the distribution of glucose meter characteristics.
Confidence in cumulative evidence
The quality of evidence for all outcomes will be judged using an adaption of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology (Grading of Recommendations Assessment, Development and Evaluation).
As a result of applying GRADE, the overall quality will be rated as:
High - further research is very unlikely to change our confidence in the estimate of clinical consequence.
Moderate - further research is likely to have an important impact on our confidence in the estimate of clinical consequence and may change the estimate.
Low - further research is very likely to have an important impact on our confidence in the estimate of clinical consequence and is likely to change the estimate.
Very low - very uncertain about the estimate of clinical consequence.