DM: Blood Glucose Self-Monitoring (2007)

Citation:

Meier JL, Swislocki ALM, Lopez JR, Noth RH, Bartlebaugh P, Siegel D.  Reduction in self-monitoring of blood glucose in persons with type 2 diabetes results in cost savings and no change in glycemic control.  Am J Manag Care 2002; 8:557-565.

PubMed ID: 12068962
 
Study Design:
Cohort study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
The study purpose was to determine if cost savings could be affected by reducing blood glucose meter testing (strip use) without compromising glucose control. 
Inclusion Criteria:
  • Patients in the Veterans Affairs California Health Care System
  • With diabetes (diet or medication treated)
  • Who received self-management blood glucose (SMBG) strip prescription fill between 7/1/97 - 12/31/97 for the baseline period 
  • Who received self-management blood glucose (SMBG) strip prescription fill between 7/1/98 - 12/31/98 for the postimplementation period
Exclusion Criteria:
  • Patients receiving insulin therapy during or within 3 months before or 2 months after the study periods
  • Patients noted to have a recent medication addition or titration may be been excluded per provider discretion.
Description of Study Protocol:

Recruitment:  Recruited as specified based on Inclusion Criteria.  Subjects were exempted from informed consent.

Design:  Cohort study.

Blinding used: Not applicable

Intervention :

  • The Veterans Affairs California Health Care System implemented a policy change April 1998 for stable patients with type 2 diabetes, not using insulin.  This policy decreased the number of home glucose monitoring strips that would be reimpbursed to 50 strips every 90 days.   A letter was sent out to 1467 patients outlining the policy change.   This policy could be overwritten by a prescription from the patient's provider if determined necessary.

 Statistical Analysis

  • Data was calculated on personal computers using Access and Excel databases.
  • Student t test
  • Paired t test
  • P < .05 was considered statistically significant

 

Data Collection Summary:

Timing of Measurements

  • Baseline
  • Postimplementation (~1 year after baseline) 

Dependent Variables

  • A1C determined by two different laboratory analyzers.  Although slight variation has been known to occur between the two analyzers, the researchers presented the unadjusted data recognizing that measurements of A1C can vary based on many individual reasons (renal function, unstable clinical status) and that any conversion factor that could be used between the two analyzers is only an approximate adjustment.  Analyzers:  Bio-Rad Variant analyzer and Tosoh A1C 2.2 plus glycohemoglobin analyzer.
  • Cost savings of strips.   This was determined by comparing the cost of strips after the intervention to the cost of strips prior to the intervention.  The strip use prior to intervention was determined by multiplying number of subjects by the prepolicy strip use.

Independent Variables

  • Strip use

 Control Variables 

Description of Actual Data Sample:

Baseline N: Global population of 1467 (98% male).  1213 of the 1467 were medication treated; 1067 of the 1467 had A1C obtained.

Post-intervention N: Global population of 1560 (98% male).  1278 of the 1560 were medication treated; 1151 of the 1560 had A1C obtained.

Cohort N: 471 individuals were in both the baseline and post-intervention populations AND had A1C values during both time periods.  421 of the 471 were medication treated.

Age: 64 ± 11 years both baseline and post-intervention time periods.

Ethnicity: Not identified.

Anthropometrics:  Not identified.

Location: Seven outpatient clinics from Northern California, USA.

 

Summary of Results:

 

Global Population Results
  Diet Controlled Medication Controlled  
Baseline Post-Implementation P Value Baseline Post-Implementation P Value
Number of Subjects (N) 154 177 913 974
A1C result (%) 6.85 ± 0.97 6.78 ± 1.20 0.56 7.83 ± 1.34 7.86 ±1.54 .63
Meter Strips used per day 1.07 ± .90 0.70 ± 0.51 <.0001 1.36 ± 0.95 0.74 ± 0.50 <.0001

 

Cohort Population Results
  Diet Controlled P Value Medication Controlled P Value
  Baseline Post-Implementation   Baseline Post-Implementation  
Number of Subjects (N) 50 50   421 421  
A1C result (%)  *  *   7.82 ± 1.22 7.66 ± 1.17**  <.05
Meter Strips used per day 1.17 ± 1.04 0.61 ± 0.44 <.001 1.35 ± 0.92 0.67 ± 0.44 <.001

* Diet controlled A1C data was not available but stated to be not significantly different from baseline to post-implementation

* A1C 7.83 ± 1.21 when data was corrected for difference between lab analyzers (no significant change from baseline)

Other Findings

The cost savings calculated following this study was figured to be $8800 per month or $6.37 per patient per month.

Glycemic control in SMBG users was compared to non-SMBG users.  A retrospective analysis was done using the same data base to identify individuals between July 1, 1997 and June 30, 1998 who filled at least one prescription for blood glucose strips, and those that did not.  A1C data was compared between these two groups.  Patients who performed SMBG (n=1055) had significantly lower A1C compared to those who did not perform SMBG (n=897) (7.84% ± 0.04 vs. 8.27%± 0.05 P<.0001).  Additional details of these groups were not noted.

 

 

Author Conclusion:
The authors conclude that given the suitable population, cooperation from the providers, nurse educators and pharmacists, a significant cost savings can be realized without compromising patient care (glycemic control).  The ideal frequency of SMBG testing remains to be determined.
Funding Source:
Reviewer Comments:

It is of interest that when compared to non-SMBG users, SMBG users had significantly lower A1C results.  However, as noted by the authors, the ideal frequency of testing is not determined by this study. 

Patient numbers in global population after implementation were larger but the proportions of SMBG testers and patients with HbA1c testing remained the same.

Limitations to the data:  testing frequency is inferred from strip prescription filling patterns, and there is a possibility that patients were obtaining SMBG strips on their own without a prescription.

Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
 
Validity Questions
  1. Was the research question clearly stated? Yes
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
  1.3. Were the target population and setting specified? Yes
  2. Was the selection of study subjects/patients free from bias? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
  3. Were study groups comparable? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? Yes
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
  4. Was method of handling withdrawals described? N/A
4. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
  5. Was blinding used to prevent introduction of bias? ???
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? ???
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? ???
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
  6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? ???
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? ???
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? ???
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
  7. Were outcomes clearly defined and the measurements valid and reliable? Yes
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? No
  7.2. Were nutrition measures appropriate to question and outcomes of concern? No
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
  8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
  9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
  10. Is bias due to study's funding or sponsorship unlikely? ???
10. Is bias due to study's funding or sponsorship unlikely? ???
  10.1. Were sources of funding and investigators' affiliations described? ???
  10.1. Were sources of funding and investigators' affiliations described? ???
  10.2. Was the study free from apparent conflict of interest? ???
  10.2. Was the study free from apparent conflict of interest? ???