NEW YORK (360Dx) – The number of diagnostic tests ordered by general practitioners in the UK have more than tripled during the past 15 years, researchers have found.
Writing in a study published Wednesday evening in The BMJ, the researchers said that from 2001-2002 to 2015-2016, the number of tests ordered per 10,000 person-years rose from 14,869 to 49,267, or an increase of 8.5 percent each year. This, in turn, has resulted in costs to the National Health Service of more than £2.8 billion ($3.6 billion) a year.
In spite of the economic burden this has placed on the NHS, threatening its sustainability, little research has been done in this area, the researchers said. For their work, they homed in on general practitioners because they account for the bulk of test orders, "with almost 45 percent of requests for tests arising from primary care."
They sifted through electronic health record data from patients registered with general practices who contribute to the Clinical Practice Research Datalink — a large database of EHRs from UK primary care — from April 1, 2000 to March 31, 2016, and studied all tests included in the CPRD primary care record for that period. They grouped the tests into one of three categories: laboratory, imaging, and miscellaneous tests, which included spirometry, upper endoscopy, colonoscopy, cervical smears, electrocardiography, and other similar tests.
Additionally, they looked at 44 specific tests that are commonly ordered — 28 laboratory, 11 imaging, and five miscellaneous — and that are included in the Quality and Outcomes Framework, a health-related pay-for-performance program initiated by the NHS in 2004.
Among the findings: patients between 45 and 64 years of age had the highest rate of test use across all the years that were analyzed, followed by 65 to 74 year-olds and 25 to 44 year-olds, the researchers said.
Laboratory tests were used "substantially more often than imaging and miscellaneous tests across the entire study period," they noted, and laboratory tests had the greatest increase among the three categories of tests in 2000-2001 (13,091 tests per 10,000 person-years) to 2015-2016 (44,847 tests per 10,000 person years), an annual increase of 8.7 percent.
The increase in imaging tests during the same period was 5.5 percent annually, while miscellaneous tests increased 6.3 percent annually.
Among specific tests, renal function tests were the most commonly ordered for the study period (2002-2003 to 2015-2016), while full blood counts were the most ordered test in 2001-2002, and was the second-most ordered test between 2002-2003 to 2015-2016.
Liver function tests were the third-most ordered test from 2001-2002 to 2015-2016, and urine dipstick testing was third in 2001-2002.
Vaginal swabbing, the researchers said, was the only test with a statistically significant annual decrease during the study period.
The increase in test utilization by gender was nearly identical. For male patients, test ordering increased 3.4-fold, and for female patients the increase was 3.3-fold. Patients older than 85 years of age had the greatest increase, 4.6-fold.
The researchers pointed to a number of reasons for the increase in testing in UK primary care, noting a greater number of consultations between patients and general practitioners "with tests reportedly being used for 'strategic, nonmedical reason,' such as reassuring patients and ending consultations."
Changes to NHS services may also be a factor, as general practitioners' access to diagnostic tests have expanded, and many services have been diverted to primary care settings from secondary care settings, the researchers said. They added that the introduction of the Quality and Outcomes Framework also may have led to an increase in diagnostic testing.
Changes to the patient-doctor relationship is another possible factor. "With the advent of shared decision-making … patients are increasingly informed and encouraged to discuss healthcare choices," the researchers said. "Evidence suggests that both clinicians and patients overestimate the benefits and underestimate the harms of tests."
Meanwhile, fear of legal action resulting from wrong or missed diagnoses may also have pushed the number of tests up, they added.
They point out, however, that not all increases in testing are inappropriate. While some tests, such as vitamin D tests, increased "exponentially" during the study period and may indicate "unnecessary screening" practices," the growth in other types of tests, such HbA1c testing may have been justified. In 2011, the World Health Organization approved HbA1c testing for the diagnosis of, as well as the monitoring of, diabetes, an event that "likely … contributed to the significant increase in HbA1c test use."
Of the £2.8 billion they estimated that the NHS spends on diagnostic testing each year, the researchers said that the true costs of such testing are probably even greater. "Our estimates only account for the direct cost of tests and do not include the cost of general practitioners reviewing the result of the administration team processing the result," they wrote.
In light of financial strains on the NHS, the researchers said, their findings "allow policymakers to assess trends in the use of tests, stratified by the type of test and the age and sex of patients. Our result will provide guidance for future healthcare resource planning."