Formulary Coverage for Antihypertensive Drugs Used in Children

Recent studies suggest increasing prevalence of primary hypertension, defined as elevated blood pressure with no known etiology, in children and adolescents^1,2 due to the childhood obesity epidemic.^1,3,4 Moreover, there is growing concern for overall cardiovascular health of the pediatric population because of concomitant increases in prevalence of hyperlipidemia and type 2 diabetes mellitus, which has prompted recommendations to start lipid-lowering drugs in children as young as 8 years old.⁵

Current recommendations for diagnosis, evaluation, and treatment of high blood pressure in children by the National High Blood Pressure Education Program (NHBPEP) Working Group suggest that, when indicated, single-drug therapy be initiated from any of the 5 antihypertensive drug classes (angiotensin-converting enzyme inhibitors [ACEIs], angiotensin receptor blockers [ARBs], β-blockers [BBs], calcium channel blockers [CCBs], and diuretics).⁶ Importantly, a recent large, randomized controlled trial in adults confirmed previous assertions that diuretics offer better protection against cardiovascular disease and are as effective, if not more effective, in lowering blood pressure than newer and often more expensive antihypertensive drugs.^7,8 This study also found that thiazide-type diuretics afforded better blood pressure control and protection against cardiovascular disease, especially for African American patients with high blood pressure.^7,8 Currently, no comparable study exists for the pediatric population that identifies the drug of choice to effectively treat high blood pressure and minimize long-term cardiovascular risk in children and adolescents.

All 5 classes of NHBPEP-recommended antihypertensive drugs have at least 1 medication that has been formally tested for safety and effectiveness in children and have available pediatric labeling information (ie, US Food and Drug Administration [FDA] approval for use in children).^6,9 The availability of antihypertensive drugs with pediatric labeling gives us a unique opportunity to study physicians’ prescribing decisions and medication choice as the prevalence of hypertension increases in the pediatric population.

Previous studies in adults have shown that limited availability and cost of medications offered by insurance plan formularies, particularly public insurance plans, influence drug utilization and physician prescribing patterns.^10-15 It is likely that formularies vary in medication availability, pediatric labeling status, and type of coverage for the NHBPEP-recommended classes of antihypertensive drugs. The purpose of our study was to describe medication availability, type of coverage, and pediatric labeling status of NHBPEP-recommended antihypertensive drugs for use in children offered by 2 insurance plan formularies, 1 private and 1 public, in Michigan.

METHODS

We conducted a cross-sectional assessment of antihypertensive drugs listed on the 2008 formularies for 1 private and 1 public insurance plan in Michigan,^16,17 using publicly available information. The private insurance plan under study is one of Michigan’s largest health management organizations, with nearly 500,000 enrolled members who all are covered under employer-sponsored insurance plans. Enrollees include many families with children and adolescents, with approximately 80,000 children 0 to 21 years old (49% of whom are female). Approximately 80% of the private plan’s members are selfidentified as non-Hispanic white. The private insurance plan covers approximately 3.4% of children in Michigan. On the other hand, the public insurance plan serves approximately 950,000 children and adolescents age 0 to 21 years in Michigan, many of whom live in poverty. The public insurance plan recipients are 50% female; 49% are self-identified as nonwhite minority racial groups. The public insurance plan covers approximately 39% of children in Michigan.

We used each plan’s formulary guide, made available to its participating providers both in electronic and paper formats, because these resources represent commonly used sources of information about insurance coverage parameters for general pediatricians. We focused on the 5 NHBPEP-recommended classes of antihypertensive drugs for use in children: ACEIs, ARBs, BBs, CCBs, and diuretics.⁶ We excluded other classes of antihypertensive drugs (eg, central α-agonists, peripheral α₁-antagonists, vasodilators, and combined α- and β-blockers) as well as combination antihypertensive drugs.

For each plan, we listed every medication offered for each of the 5 antihypertensive drug classes through that plan’s formulary (ie, medication availability). We characterized coverage type as preferred drug (tier 1) or requiring prior authorization (tier 2/3). We classified pediatric labeling status based on drug summaries found in the Thomson Micromedex Healthcare Series, updated quarterly.¹⁸ All antihypertensive drugs under study with a pediatric indication for use were considered as having pediatric labeling regardless of age or indication criteria. Several antihypertensive drugs did not have specific age criteria associated with pediatric indications and thus were considered to have approval for all age groups. The study was approved by the institutional review board of the University of Michigan Medical School.

RESULTS

Medication Availability and Coverage Type The complete list of antihypertensive medications and medication characteristics offered by the 2 insurance plans under study is presented in the eAppendix (available at www.ajpblive.com). Medication availability by drug class and insurance plan coverage is summarized in

Table 1

. Both plan formularies offered multiple choices for the NHBPEP-recommended drug classes of ACEIs, ARBs, BBs, and CCBs, with similar availability. However, for diuretics, the private plan offered 28 medications, whereas the public plan offered diuretics only in combination antihypertensive medications, with no single-drug availability.

The private plan formulary offered more ACEIs and diuretics as preferred drugs than the public plan. However, the public plan formulary offered more ARBs, BBs, and CCBs as preferred drugs than the private plan.

Pediatric Labeling Status of Antihypertensive Drugs

Table 2

summarizes the availability of antihypertensive drugs with pediatric labeling information. Overall availability was similar between the private and public plans for ACEIs, ARBs, BBs, and CCBs; the private plan formulary had more availability of diuretics with pediatric labeling. With regard to coverage type, the private and public plans had similar numbers of pediatric-labeled drugs offered as preferred drugs, with the exception of diuretics. Both plan formularies included a number of antihypertensive medications that did not have pediatric labeling (84 for the private plan vs 66 for the public plan).

DISCUSSION

Previous studies have generally shown that compared with their privately insured counterparts, the publicly insured population has less choice and more restriction on formularies.^15,19,20 However, the private and public insurance plan formularies in our study offered similar choices of antihypertensive drugs from 4 of the recommended subclasses for use in children, and similar insurance plan coverage. This finding counters the perceived current paradigm in adults that medication availability is broader in private than public insurance plans.

Moreover, availability of antihypertensive drugs with pediatric labeling was similar between the public and private plans, as was coverage of preferred drugs. Pediatric labeling requires FDA-approved testing to establish safety and efficacy for a given medication for use in children. It provides important information about a medication’s indication and usage, dosage and administration, contraindications, and adverse effects that can guide physicians’ prescribing practice for children. Thus, availability of antihypertensive drugs with pediatric labeling as preferred drugs is essential to ensure safe and effective therapeutic alternatives for pediatricians in their efforts to combat the increasing prevalence of high blood pressure in children.

The exception to this study’s pattern of results was diuretics, which were not listed as single-drug therapy on the public plan’s electronic and hard-copy formulary reference guides made available to its participating providers. The absence of diuretics was surprising; therefore, we verified the authenticity of our findings by examining the plan’s formularies from prior years, and found a similar absence of diuretics as single-drug therapy. When we contacted the public plan’s medical director for clarification, he provided a separate, more exhaustive list of medications that did include many diuretics (including thiazides) as single-drug therapy. Thus, the commonly referenced version of the public plan formulary was inaccurate because diuretics as single-drug therapy were omitted when in fact these medications were offered. Importantly, a busy clinician at the point of care may be inadvertently steered away from prescribing these cost-effective diuretics, given the inaccurate information on the widely disseminated version of the public plan formulary.

Studies in adults have shown that diuretics offer good blood pressure control and better protection against cardiovascular disease than other newer and often more expensive antihypertensive drugs, particularly for African American patients.^7,8 Given that low-income, publicly insured minority children are disproportionately affected by the childhood obesity epidemic,^21-27 the public insurance plan should correct the information regarding diuretic availability so that the cardiovascular health of this high-risk group is not negatively impacted by inadvertent promotion of antihypertensive medications with potentially less favorable clinical outcomes.

Our study is a brief, baseline assessment at a single point in time. We focused only on medications listed on insurance plan formularies and the available choice offered by different insurance plans. Our study design did not assess provider prescribing patterns, drug utilization, or clinical outcomes. Also, we looked at only 1 private and 1 public insurance plan in Michigan; other plans within and outside the state may have different coverage patterns. However, both plans included in this study are large insurance plans serving enrollees of diverse racial and socioeconomic backgrounds similar to those served by other insurance plans outside of Michigan.

CONCLUSION

Contrary to the perceived current paradigm, the overall availability of antihypertensive drugs was similar between the private and public plans in this study. The public plan’s apparent lack of coverage for diuretics as single-drug

therapy may warrant further study to ensure that providers and patients are not being steered away from cost-effective first-line antihypertensive therapy. Efforts to improve formulary development and implementation for both private and public insurance plans should include readily accessible and user-friendly formularies that highlight medications with a proven record of safety, efficacy, and cost-effectiveness.