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Lyme patients report higher QOL over time than general population
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Persons diagnosed with Lyme disease appeared to achieve an average quality of life score greater than that of the general population over time, with patients reporting reduced health or long-term subjective symptoms often experiencing comorbidities unrelated to Lyme infection, according to a recent longitudinal analysis.
“A minority of treated patients continue to report persistent or relapsing nonspecific symptoms; it is estimated that up to 20% of patients with [erythema migrans] have persistent or intermittent subjective symptoms of mild to moderate intensity 12 months after therapy completion,” the researchers wrote. “We aimed to describe trends in Lyme disease symptoms, laboratory results and [quality of life (QOL)] to better understand the impact of infection over time, and better inform clinical practices for managing Lyme disease patients.”
Reports of reduced QOL associated with comorbidities
Researchers enrolled adults with confirmed Lyme disease enrolled in a natural history study run by the NIH from 2001 to 2014. Included participants had a minimum 6 months of follow-up, but often received annual evaluations for several years. Demographic and clinical data were collected at baseline, and a standardized QOL survey was completed by participants at each follow-up visit. Pre-existing comorbidities were self-reported by the patients at baseline and validated by clinical staff or prescribed medications. With these information, the researchers identified QOL trends and estimated risk ratios using both univariate and multivariate models.
Of the 101 patients meeting inclusion criteria, 96% completed at least one questionnaire, and 59% provided baseline forms, combining for 357 usable questionnaires. The mean age of participants, who were predominantly white, was 49 years. Median study follow-up time was 3.4 years. Fifty-eight percent of the patients had untreated Lyme disease at study enrollment, 91% reported at least one symptom at baseline, 57% reported at least one active comorbidity at enrollment, and 87% did not report a previous Lyme disease diagnosis.
The cohort’s overall mean QOL scores were below the general population mean for physical and mental health at first visit. After 3 years of follow-up time, however, these scores exceeded the national average. QOL scores often were different between patients with different forms or stages of disease, but also generally increased over time.
Patients with long-term Lyme symptoms were more likely to report mental or behavioral health conditions (adjusted RR = 1.7; 95% CI, 1.2-2.5) or obesity (aRR = 1.6; 95% CI, 1.1-2.4), and each additional comorbidity reported at baseline increased a patient’s likelihood of reporting long-term symptoms by 13%. Patients with low physical QOL scores were twice as likely to report a comorbidity associated with chronic pain at baseline, with each additional reported comorbidity increasing the chance of low baseline scores by 24%. Patients with lower mental QOL scores were also twice as likely to have mental or behavioral health conditions at baseline, and threefold odds of taking medications for mental health conditions.
“Only pre-existing comorbidities — and not Lyme disease stage or severity — were predictive of having lower QOL measures and long-term symptoms,” the researchers wrote. “Comorbid conditions should be considered when evaluating patients with Lyme disease suffering from long-term symptoms and reduced QOL.”
Lyme disease vectors spreading throughout continental US
The risk for new cases of Lyme disease may be of increasing concern, as surveillance data reported earlier this year also suggest the prevalence of Lyme disease’s primary vectors — Ixodes scapularis and I. pacificus — has substantially risen in the United States.
To update the 1998 distribution data of these species, Rebecca J. Eisen, PhD, research biologist in the vector-borne disease division at the CDC, and colleagues reviewed literature published from Jan. 1, 1996 to Aug. 25, 2015 for studies and articles related to the vectors. These, along with data from state health department websites and public health officials and investigators, were used to update county estimates after the same classifications used in the 1998 publication.
According to the researchers, I. scapularis was collected from 37 states and 45.7% of continental U.S. counties, while I. pacificus was found in six states and 3.6% of counties. Combined, these Lyme vectors have been identified in 49.2% of continental counties and 43 states, a distribution that the researchers wrote is a 44.7% increase over the previously reported surveillance report. The number of counties in which I. scapularis was considered to be established increased from 12.7% of counties in 1998 to 27.1% of counties in 2015, while the portion of U.S. counties with established I. pacificus rose modestly from 2.9% to 3.1% among the Western states.
“This study shows that the distribution of Lyme disease vectors has changed substantially over the last nearly 2 decades and highlights areas where risk for human exposure to ticks has changed during that time,” Eisen said in a press release. “The observed range expansion of the ticks highlights a need for continuing and enhancing vector surveillance efforts, particularly along the leading edges of range expansion.” – by Dave Muoio
Disclosure: The researchers report no relevant financial disclosures.
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