Very few Lyme disease studies consider sex- and gender-based differences. Is this flawing the research?
A common misconception is that men and women have comparable physiological and pathological disease responses. However, a demographic breakdown of study participants, including by gender, is crucial to comprehend trial results. This is why, since 2015, the National Institutes of Health (NIH) has stipulated that sex be included as a biological research variable.
However, sex differences in Lyme disease pathology have not been meaningfully analyzed. The Centers for Disease Control and Prevention (CDC) estimates there are 476,000 new Lyme disease cases each year in the United States. Caused by the spirochete Borrelia burgdorferi and transmitted by black-legged ticks, Lyme disease is the most common vector-borne disease in the US.
One study, published in the International Journal of General Medicine, sought to assess sex-based differences in Lyme disease patients who were clinically diagnosed and reported ill for at least 6 months after antibiotic treatment.
Most patients who receive early diagnosis and treatment can recover without complications. However, 43% report persisting symptoms for 6 months or more after antibiotic treatment, and only 57% were classified as fully recovered.
This study analyzed data from the MyLymeData registry, which included over 2000 patients with persistent or chronic Lyme disease (PLD/CLD). The investigators described sex-based differences in PLD/CLD related to symptom severity, diagnostic delays, misdiagnosis, and functional impairment, as well as treatment response and adverse events.
The investigators analyzed self-reported clinical data from the 2170 patients in the MyLymeData registry. They also reviewed prior Lyme disease studies to gauge the distribution of participants by biological sex according to illness stage, data source, and definition of disease.
According to MyLymeData, women reported more tick-borne coinfections, worse symptoms, longer diagnostic delays, more misdiagnoses, and worse functional impairment than men. There were no notable differences, however, in antibiotic treatment or adverse events.
“Women had more severe symptoms and were more likely than men to report being disabled, spending more days in bed, and requiring special equipment as a result of their PLD/CLD,” wrote the study authors. They also noted a smaller percentage of women in acute Lyme disease studies, and a larger percentage of women in studies of PLD/CLD.
“Our results indicate that biological sex should be integrated into Lyme disease research as a distinct variable,” the study authors concluded. “Future Lyme disease studies should include sex-based disaggregated data to illuminate differences that may exist between men and women with persistent illness.”