Introduction
Materials and methods
Results
Indicator | Description | References |
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Hypoglycaemiaa | Represented in different ways. In most studies it is represented as the number or percentage of measurements below a certain BGL value and/or number or percentage of patients who experienced at least one measurement below a predefined BGL value | |
BGLs over time | Represented as mean and/or median BGL values. Each BGL measurement or each patient was regarded the unit of observation. In one study, it was calculated as area under the glucose/time curve divided by total time per admission [10]. Mean or median BGL was also calculated: • at the end of IIT [52]; • for patients who had admission BGL above a threshold [10]; • after 24 hours [15]; or | |
Measurements in predefined BGL ranges | Represented as the number or percentage of measurements in a predefined BGL range: • during the study; • at the start of IIT [21] Each BGL measurement, and in one study each patient [11], was considered the unit of observation | |
Time to capture defined BGL target | Represented as: • mean and median of time; or In one study two successive BGL measurements in the target range were required before calculating time [20] | |
Frequency of measurements during the study | Represented as: • median frequency per patient-hour [23]; • percentage of patients with more than one measurement in predefined time interval (every 2 hours, and so on) [31]; • percentage of time in which at least one measurement per 2 hours was taken [32]. | |
BGL at starting IIT | Represented as mean and median BGL | |
Protocol compliance | ||
Time in predefined range | Represented as: • median of fraction of time per day [29]; • percentage of time 24 hours before, within and after trial [39] | |
Hyperglycaemic events | Represented as: • percentage of time >180b, >250 (severe hyperglycaemia) [16], or between 151 and 200 and >200 (severe hyperglycaemia) [21]; • percentage of patients with at least one measurement per day ≥ 250 and ≥ 200) [22]; • percentage of measurements and patients with at least one BGL above the 180 level for more than 2 hours [13] | |
Morning BGLs | Represent as: • mean BGL around 06:00 hours [43], between 06:00 and 12:00 hours [50], or between 06:00 and 09:00 hours [19]; • mean lowest BGL between 06:00 and 09:00 [43]; • mean of BGL, but morning time was not mentioned [20] | |
Hyperglycaemic index | Represented as median area between glucose-time curve and upper normal range divided by time per patient during the trial [15, 24], in first 24 hours [23, 25] or in first 48 hours [17]. Upper normal range was 207 [23], 117 [15], 108 [24], 120 [17], and 150 [25]. It was calculated with the same definition but without labeling as hypoglycaemic index [23, 25] | |
Time until starting or adjusting IIT | ||
Minimum and maximum recorded BGL | Represented as: | |
Number of patients with at least one BGL in predefined range | ||
BGL change over time | Represented as: • speed of BGL change per hour [54]; or • BGL change in first 24 hours [15] | |
Number of patients who achieved or did not achieve target or predefined range | Represented as number and percentage | |
Number of positive culture | Represented as median (per patient) or rate (per year per patient). | |
Target acquisition error | Represented as absolute value and percentage of difference between the target BGL and achieved BGL |
Indicator | Description | References |
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Adequate daily blood glucose control | Represented as median hours spent each day within the target range per patient | 1 article [21] |
Correlation between within-run mean BGL and within-run mean coefficient of variance for hourly insulin rate | To illustrate whether hyperglycaemia after attaining target is correlated with variability in infusion rate | 1 article [9] |
Correlation between within-run mean BGL and within-run mean hourly insulin rate | To illustrate whether the protocol performed equally well independent of insulin resistance | 1 article [9] |
Distribution of the individual patient BGL mean in a predefined time interval | Represented in box plot | 1 article [11] |
Number of patients with well and poor BGL control | Represented as percentage of patients and defined as: • well controlled patient: <130a BGL for more than half of the measured time; or • poor controlled patient: <130 BGL for less than or equal to half of the measured time. | 1 article [31] |
Odds ratio of achieving certain BGL | Per additional Intensive Care day and some drugs | 1 article [50] |
Number of patients having defined mean BGL | Represented as percentage of patients with mean BGL ≥ 200 for each day after surgery | 1 article [22] |
Probability density function for BGL measurements | Represented as a curve for comparison with other protocols | 1 article [35] |
Proportion of patient-day with mean BGL<200 and ≥ 200 and IIT at least in part of the day | 1 article [22] | |
Number of report on necessary departure from protocol, clinical intervention or adverse events | 1 article [35] | |
Time from admission to first BGL | Represented as mean of time [15] | 1 articles [15] |
Variability after achieving target | Represented as within-run mean (IIT episode) ± standard deviation and mean of within-run coefficient variance ± standard deviation (%) | 1 article [9] |
Hypoglycaemia (adverse-zone and time categories)
Indicators | Description | Reference |
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Hypoglycaemic events | Reported thresholdsa for defining a BGL as hypoglycaemic event: • ≤ 40 [26]; • <54 [34]; • <57 [32]; • <63 [23]; • <65 [25]; • <72 [20]; or • threshold was not reported [48] Represented as: • percentage and number of measurements and/or patients with hypoglycaemic event during the trial, or normalized for duration of therapy [16]; • mean or median of events per patient-day [57]; • mean of events per patient [27]; • patients with at least one event per day [22]; or | |
Severe or marked hypoglycaemic events | Reported threshold for defining a BGL as severe hypoglycaemic event: • <48 [24]; or • in one study clinical finding defined as severe hypoglycaemia [8] Represented as: • percentage and number of measurements and/or patients with severe hypoglycaemic event; • mean or median of events per patient-day [29]; | |
Need for dextrose injection | Reported threshold for dextrose injection: • <45 [29]; • <54 [44]; • <60 [53]; • <63 [23]; • <65 [25]; or Represented as: • percentage and number of dextrose injections [25] | |
Mild or moderate hypoglycaemic events | Reported threshold for defining an BGL as severe hypoglycaemic event: • 40–59 [42]; • <60 [46]; • 40–60 [51]; • <63 [15] Represented as percentage and number of measurements and/or patients with a moderate hypoglycaemic event | |
Hypoglycaemia duration | ||
Time until next in predefined range after hypoglycaemia | ||
Duration of stopping IIT because of hypoglycaemia | Represented as median of percentage of time per patient | |
Next BGL after hypoglycaemia | Represented as mean BGL | |
Time until reaction to hypoglycaemic event | ||
Time from starting IIT until first hypoglycaemia | Represented as mean time | 1 article [19] |
Time till next BGL after hypoglycaemia | Represented as mean time | 1 article [49] |
BGL summaries over time (BGL category)
Measurements and time in predefined BGL ranges (in-range zone and time categories)
Time to capture the defined BGL target (time category)
Hyperglycaemic indicators (adverse zone category)
Sampling of BGL during the study, BGL at starting TGC and adherence to protocol (protocol category)
Discussion
Conclusion
Key messages
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TGC indicators differ widely in their definitions, even when they are meant to measure the same underlying concept.
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Many definitions of indicators are not precise, limiting their applicability and hence the reproducibility and comparability of research findings.
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An unambiguous indicator reference subset is necessary for evaluating quality of TGC.
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The result of this systematic review can be used as a starting point from which to develop a standard list of well defined indicators, which are associated with clinical outcomes or concur with clinicians' subjective views on the quality of the regulatory process.