Testing company evaluates Rx misuse

A report issued by diagnostic testing provider Quest Diagnostics adds some new numbers to the ongoing discussion of the extent and impact of prescription drug misuse in the nation. The sheer size of the analysis, encompassing a sample of nearly 76,000 de-identified urine specimen results, gives reason for close examination of the results.

The results, formally released by the Madison, N.J.-based company in April, indicate that most patients receiving prescription medication from their doctors misuse that medication to some degree. In addition, prescription misuse is relatively prominent in all age groups, according to the analysis.

The study also reported that follow-up drug testing that was conducted at least 30 days after an initial screen resulted in a 10% drop in the number of inconsistencies observed through testing.

The report’s authors state, “Our data supports medical recommendations that physicians perform routine urine testing to monitor prescription drug misuse.”

The numbers

Quest Diagnostics’ analysis looked at a national sample of 75,997 urine test results from 2011. The tests employed Quest Diagnostics’ proprietary prescription drug monitoring service and its reporting methodology. The analysis examined whether test results were consistent with the physician orders for each individual receiving prescription medication.

The study found inconsistency with physician orders in 63% of cases. In general, there were two categories of problems uncovered. In 60% of the inconsistent cases, there was evidence of the presence of drugs that had not been specified by the physician ordering the test. This encompassed both situations in which the prescribed drug was being used in addition to at least one other drug and those in which someone tested positive for another drug but not the prescribed drug.

In 40% of the inconsistent cases, testing revealed the presence of no drug in the patient’s system. The study cites several possible explanations: “It is possible that some patients cannot afford their medications, and skip days (or do not take the drug), while others divert drugs, including potentially selling them to others.”

The highest risk of misuse in the sample occurred in the 18-to-24 age group, with 73% of test results in that group showing inconsistency with physician orders. The percentage of inconsistent tests generally decreases from younger age group to older age group, although the 65-plus age group still sees exactly half of its tests demonstrating inconsistencies in this analysis.

While men were more likely than women to test positive for illegal drugs such as cocaine or marijuana, overall inconsistency rates in tests for men and women were the same, the researchers found.

Inconsistency rates also were relatively similar in lower- and higher-income communities based on median income data by zip code. However, the study did find that patients covered by Medicaid exhibited less consistency with physician orders than did patients covered by Medicare or private insurance. The authors stated, “Our finding that a large number of government beneficiaries are misusing prescription medications is a source of concern, given efforts by states and the federal government to fund overburdened government healthcare programs.”

Impact of testing

As part of its analysis, Quest Diagnostics examined data for 6,858 patients who were drug tested at least twice, with the tests taking place 30 days or more apart. The researchers found that in this subgroup, the test inconsistency rate with the second test dropped from 62% to 55%.

In a separate examination of patients tested at least twice for the presence of opiates, oxycodone and methadone, the test inconsistency rate dropped from 41% to 34%. The researchers stated in their report, “The improvement was particularly striking for patients who were inconsistent on their first screen for the pain medications: 50% of these patients were consistent on repeat testing. However, these favorable findings were tempered by data showing that more than 23% of patients whose tests were consistent on an initial screen were inconsistent with repeat testing.”

The study pointed out that none of the test results included those of patients being treated in drug treatment centers, “given the unusually high rates of drug inconsistency expected of this clinical segment.”

The study points out that while physicians have several tools at their disposal for monitoring their patients who receive prescription medications, research suggests that application of these tools in everyday practice remains spotty. They wrote, “In addition, some patients may mislead their physicians about their drug use and urine drug tests may therefore provide an objective basis for assessing appropriate medications.”

Several organizations have advocated urine testing as part of the process for monitoring use of prescribed and non-prescribed medications in certain groups of patients, the report states. These include the American Pain Society and American Academy of Pain Medicine, in their jointly issued 2009 guidelines for use of chronic opioid therapy for chronic non-cancer pain.