Original Research

Predictors of HA1c Goal Attainment in Patients Treated With Insulin at a VA Pharmacist-Managed Insulin Clinic

Fed Pract. 2018 November;35(6):S18-S22

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Methods

This study was performed as a single-center retrospective chart review. The protocol and data collection documents were approved by the CMCVAMC Institutional Review Board. It included patients referred to a pharmacist-led DSM clinic for insulin titration/optimization from January 1, 2011 through December 31, 2012. Data were collected through June 30, 2013, to allow for 6 months after the last referral date of December 31, 2012.

This study included patients who were on insulin therapy at the time of pharmacy consult, who attended at least 3 consecutive pharmacy DSM clinic visits, and had an HbA_1c ≥ 8% at the time of initial clinic consult. Patients who failed to have 3 consecutive pharmacy DSM clinic visits, were insulin-naïve at the time of referral, aged ≥ 90, lacked at least 1 follow-up HbA_1cresult while enrolled in the clinic, or had HbA_1c < 8% were excluded.

Among the patients who met eligibility criteria, charts within the Computerized Patient Record System (CPRS) were reviewed in a chronologic order within the respective study time frame. A convenience sample of 100 patients were enrolled in each treatment arm: the goal-attained arm or the goal-not-attained arm.

The primary study variable was HbA_1c goal attainment, which was defined in this investigation as at least 1 HbA_1creading of < 8% while enrolled in the DSM clinic during the review period. Secondary variables included specific patient factors such as optimal frequency of self-monitoring of blood glucose (SMBG) testing, adherence to pharmacist’s instructions for changes to glucose-lowering medications, adherence to bringing glucose meter/glucose log book to clinic appointments, and percentage of visits attended. Definitions for each variable are provided in Table 1.

Data were collected for the 4 months prior to the date of at goal HbA₁_c. For patients in the goal-not-attained group, the secondary variables were collected for the 4-month period prior to the end of follow date. This final date was determined as either the last pharmacy visit date due to loss of follow-up or end of data collection time frame of June 30, 2013.

We hypothesized that patients who were more adherent to treatment plans, regularly attend clinic visits, and appropriately monitor their glucose levels were more likely to meet their glycemic goals.

Statistical Analysis

Univariate descriptive statistics described the individual variables/predictors of HbA_1c goal attainment. As the study’s purpose was to identify patient factors and characteristics associated with HbA_1cgoal attainment, a logistic regression model framework was used for all covariates to evaluate each measured variable’s independent association with HbA_1c. The univariate tests were used to compare patient characteristics between the 2 study groups: Pearson chi-square test was used for nominal data, and a paired t test (for normally distributed data) or Wilcoxon rank sum test (for non-normally distributed data) was used for continuous variables. Variables having a P value < .2 underwent a multivariate analysis stepwise logistic regression model to identify patient factors and characteristics associated with HbA_1c goal attainment. A Fisher exact test was used to determine gender effect on HbA_1c goal attainment, categoric variables were analyzed using Pearson chi-square test, and an unpaired t test was used for continuous data. The backward elimination approach to inclusion of variables in the model was used to build the most parsimonious and best-fitting model, and the Hosmer-Lemeshow goodness-of-fit tests was used to assess model fit. Data analyses were performed using IBM SPSS, version 18.0 (Armonk, NY).