Lyme neuroborreliosis diagnosis had no substantial effect on long-term survival, health, or educational/social functioning yet may be associated with an increased risk of hematologic and nonmelanoma skin cancers, according to a 30-year study published in the BMJ.
Niels Obel, MD, PhD, from the Department of Infectious Diseases at Copenhagen University Hospital, and colleagues used a population-based nationwide cohort design to compare long-term survival, health, social functioning, and education among patients with Lyme neuroborreliosis and a comparison cohort from the general population.
For each patient with Lyme neuroborreliosis, the researchers identified all Danish residents with the same sex and date of birth as the patient who had not tested positive for B burgdorferi intrathecal antibodies and who met the study’s inclusion and exclusion criteria (other than a diagnosis of borreliosis). From this population, 10 random people were matched for each patient to complete the comparison cohort.
The researchers ascertained time to death, diagnoses of cancers, and potential medical sequelae (supplementary appendix). They calculated time from date of study inclusion to March 1. 2016, death, emigration, loss to follow-up, or event of interest, whichever came first. The investigators calculated mortality rate ratios and incidence rate ratios as measures of relative risk and included patients registered with a diagnosis of borreliosis in the DNPR up to one year after study inclusion.
During the study period, 3,200 people were identified with a positive B burgdorferi intrathecal test. Of these, 1,047 (33%) did not have a diagnosis of borreliosis recorded in the DNPR and 86 (3%) were registered as having had contact with a department of neurology more than one year before study inclusion. After these exclusions, 2,067 patients and 20,670 members of the population comparison cohort remained in the study.
Mortality among patients with Lyme neuroborreliosis was not higher than in the general population (mortality rate ratio, 0.90). Lyme neuroborreliosis patients had an increased risk of hematologic (incidence rate ratio, 3.07) and nonmelanoma skin cancers (1.49). At diagnosis, Lyme neuroborreliosis patients had slightly higher employment and lower disability pension rates.
After 5 years, patients and comparison cohort members had similar numbers of hospital contacts (difference −0.22, 95% confidence interval −0.45 to 0.02, in-hospital days/year; 0.37, −0.10 to 0.83, outpatient visits/year), employment rates (difference 1.5%, −2.1% to 5.1%), income (difference −1000, −20 000 to 18 000, Danish kroner), days of sick leave (difference −0.3, −3.5 to 3.0, per year), rates of receipt of a disability pension (difference −0.9%, −3.2% to 1.3%), and number of children (difference –0.10, −0.27 to 0.08). More patients were married (difference 4.8%, 2.2% to 7.4%) and had completed high school education (difference 7%, 1% to 12%).
“Compared with members of a general population cohort, mortality was not increased among Lyme neuroborreliosis patients,” the authors concluded. “However, Lyme neuroborreliosis patients had an increased risk of hematological and non-melanoma skin cancers.”
Obel N, Dessau RB, Krogfelt KA, et al. Long term survival, health, social functioning, and education in patients with European Lyme neuroborreliosis: nationwide population based cohort study [published online May 30 2018]. BMJ. doi: 10.1136/bmj.k1998.