Consumers who have complex medical diagnoses that require specialty drugs should carefully examine the health insurance plans offered through the public exchange system to avoid incurring high costs for those drugs. But that task will be complicated by inaccuracies on the public exchange website.

That’s the conclusion of an analysis of public exchange plans by Avalere Health. The study, in which researchers went through all available plans looking for “hidden” drug costs, found that silver plans in particular tend to place such drugs in specialty tiers in their 2015 formularies. Avalere said that 17 percent of silver plans contain two or more specialty drug tiers that will drive up out-of-pocket costs for those patients covered by the plans.

Even consumers who do their homework to try to avoid such costs may still wind up incurring them because of inaccurate data about out-of-pocket costs for drugs that can be found on the federal exchange website HealthCare.gov.