This population-based study examined the impact of the ADA consensus statement on baseline and annual testing of serum glucose and lipids for SGA-treated adults within a commercially insured population. We found that baseline and annual glucose and lipid testing rates for SGA-treated patients increased between 2001 and 2006. However, the rising trends in testing appear to be attributable to increases observed in background testing trends rather than a specific response to the ADA consensus recommendations. Importantly, metabolic testing remained suboptimal for SGA users. By the end of 2005, 75% of SGA users received no baseline glucose testing and 90% received no baseline lipids assessment. Annual rates of testing were more favorable; nonetheless, half of the SGA-treated adults received no glucose testing and two-thirds no lipid testing in the year following drug initiation.
This study identified metabolic testing based on laboratory claims from multiple outpatient settings within the commercial health plan. However, it was not possible to confirm whether tests were ordered by, or were available to, clinicians responsible for SGA treatment decision making. It is almost certain that some proportion of testing was performed for purposes other than the recommended evaluation of SGA effects on glucose or lipid levels. Therefore, the absolute rates of glucose and lipid testing we observed for SGA-treated patients are likely overestimates of actual metabolic monitoring related to SGA treatment.
Although this retrospective study was not able to look into the reasons why laboratory screening did not increase after the ADA consensus statement, we might speculate on some possible explanations. On one hand, the results are not surprising because typically half of physicians follow any given clinical guideline (19
). Adoption of other monitoring recommendations following drug warnings has also been poor (20
). Many causes of low adherence to evidence-based treatment recommendations have been studied, including low awareness, lack of medical consensus, low self-efficacy to enact change, and failure to overcome the inertia of previous practice (21
). Another explanation offered is that physicians treat guidelines more as options as opposed to true standards and professional organizations, such as the ADA and American Psychiatric Association, cannot enforce adherence (19
On the other hand, the low rates of serum testing observed in this study population are surprising given high awareness among psychiatrists of the metabolic risks associated with SGA medication and strong agreement on the need to screen and monitor patients (22
). After the consensus statement, 60–80% of psychiatrists reported monitoring glucose and lipid levels at regular intervals (22
). It could be that surveyed psychiatrists were not representative of all SGA prescribers. Alternatively, poor patient follow-through between the physician ordering the lab and the patient getting blood drawn may be occurring. More research is needed to determine why the gap exists between reported monitoring behavior and observed serum testing before improvements can be made in diabetes and dyslipidemia screening and ongoing monitoring for these at-risk patients.
The ADA consensus statement (13
) and subsequent published research (1
) have acknowledged that not all antipsychotics have the same metabolic riskprofile; for example, olanzapine, in particular, has been cited as having a high risk for weight gain, metabolic disturbances, and dyslipidemia (1
). As an alternative to greater vigilance in metabolic monitoring, some physicians may have started avoiding drugs with greater metabolic risk. The finding that olanzapine's share of new starts dropped from 48 to 25% after the statement is consistent with this hypothesis. Nevertheless, the FDA class warnings (14
) and the ADA consensus statement (15
) call for metabolic monitoring in all patients regardless of which SGA medication they are receiving.
The results of this research are subject to limitations. Because we relied on administrative claims records, we could not evaluate the impact of the consensus statement on unbilled metabolic screening (e.g., family history of diabetes, height and body weight, or waist circumference) or testing occurring during a hospital admission. Caution should also be applied in generalizing findings to all patients initiating antipsychotic medications, for example Medicaid clients. In addition, anecdotal reports suggest some local mental health treatment centers have been successful in increasing rates of glucose and lipid testing using incentives (e.g., financial compensation to the ordering clinician) or disincentives (e.g., sharing individual clinician performance rates among a peer group).
In summary, despite psychiatrist awareness of metabolic risk and high rates of self-reported screening, we found little evidence that patients starting SGA medication typically receive serum glucose and lipid testing. Although a gradual increase in screening rates occurred over the 6-year period, publication of the ADA consensus statement on SGA drugs and diabetes risk was not associated with an increase in aboratory testing rates. Results from this study of commercially insured patients suggest a considerable gap remains between clinical practice and ADA recommendations for routine metabolic monitoring in a population at increased risk for diabetes and cardiovascular disease. More effort is needed to ensure that patients receiving SGA drugs are screened for diabetes and dyslipidemia.