By Awah Bodunrin in Uncategorized on March 14, 2025.
By: Chad E Cook PT, PhD, FAPTA
Definition: The natural history of a disease refers to the progression of a disease in an individual over time, from its onset (pathological or exposure to causal agents) to its resolution. It is generally considered “natural” when no interventions are used that could affect the resolution process [1,2]. Natural history should encompass both the subclinical phase (when the disease is asymptomatic) and the clinical phase (when symptoms are apparent), thus how the “episode” of the disease is defined is of considerable importance. Other terms used to represent natural history include disease progression, course over time, epidemiological trajectory, or disease lifecycle.
Favorable Outcomes: Historically, most musculoskeletal conditions, specifically, low back pain (LBP) are thought to have a favorable natural history. For example, in an older, very well cited paper, it was stated that LBP episodes are self-limiting, suggesting that 90% of patients recover in 6 weeks without loss of function [3]. As such, natural history is commonly factored in to the management process for individuals with LBP in clinical practice guidelines and dedicated treatment strategies. Most clinical practice guidelines have nominal suggestions for acute LBP (pain less than six weeks) when compared to chronic LBP, as it is thought to resolve on its own [4,5]. Stepped care strategies for managing LBP often align with the concept of natural history, and emphasize non-invasive, self-management approaches as the first step, allowing the natural recovery process to take its course [6].
Unfortunately, our understanding the natural history of conditions such as LBP is less clear than what we might think. This is because the process of measuring natural history has varied markedly across studies and is highly dependent on a number of factors [7].
How is a bout or episode of low back pain defined? As a reminder, natural history is thought to include the preclinical phase. Consequently, true natural history must initiate with individuals who have no LBP who are tracked over time and then evaluated. Tracking individuals who presently have LBP or have a history of LBP are less likely to provide a true natural history of the condition, since it is well known that prior LBP influences future LBP. Tracking those with prior LBP is still valuable, but should be seen a variant of history.
What are the analytic methods used in studying natural history? Many designs have been used to measure natural history, including longitudinal cohort (prospective and retrospective), and registries. However, in most cases individuals are included in studies when they are receiving a treatment for the condition. True natural history requires no outside intervention that might interfere with the natural recovery process.
How is “recovery” defined? Many natural history studies vary on how they define “recovery”. Should recovery represent “pain free” activities, or meeting a predefined threshold of function? Should recovery represent the thoughts of the person with LBP or the investigator? Unfortunately, this is highly inconsistent across studies and often does not factor in the thoughts of the individual with LBP.
How frequently is follow up evaluated? Collecting longitudinal data is costly and burdensome. Most trials capture data at baseline and at selected points afterwards, such as 6 weeks, 3 months, 6 months and 1 year. Yet it is imperative to capture more granular. This reduces recall bias and improves the accuracy of the reflection. Thus, natural history studies require more frequent data capture that accurately reflect how recovery is defined.
Was loss to follow up evaluated? Nearly all studies lose some individuals in the process of longitudinal evaluation. Evaluating whether these individuals are different than those who remain in the study is important, as they may represent early recovery or later/no recovery.
Were intensity fluctuations accounted for in the evaluation? Most natural history studies look only at the timepoint of recovery from the initial condition. As importantly, the fluctuations that occur can represent the burden of the condition of the patient. Granular data that looks at the fluctuations during the recover process will improve our understanding of the natural history of a condition.
Recent studies have shown that the course of back pain is highly variable, occurring in transient, recurrent, and chronic phases. Longitudinal studies suggest that back pain is typically a recurrent condition and that chronic phases of LBP occur more often than previously believed [7]. Residual, less severe, back pain often persists for 1 to 3 months [8]. Ongoing discomfort greater than 3 months does not necessarily imply a more serious pathology, it is however, common [8]. Further, for those who have a history of LBP, who experience another bout or flare up, the natural history at one, five, ten and 28 years, is less favorable, suggesting once it is present, it tends to remain [9]. Lastly, natural histories also vary broadly in individuals with the same levels of severity [10].
So, is the natural history of LBP favorable? Well…..it depends.
References
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Center for Disease Control. Introduction to Epidemilogy. Download on March 12, 205 from: https://archive.cdc.gov/www_cdc_gov/csels/dsepd/ss1978/lesson1/section9.html
Waddell GA: New clinical model for the treatment of low-back pain. Spine 12:632-644, 1987.
Smedley J, Inskip H, Cooper C, Coggon D. Natural History of Low Back Pain: A Longitudinal Study in Nurses. Spine 1998;23(22):p 2422-2426.
Casazza BA. Diagnosis and treatment of acute low back pain. Am Fam Physician. 2012 Feb 15;85(4):343-50.
Fritz J, Rhon D, Teyhan D, et al. A Sequential Multiple-Assignment Randomized Trial (SMART) for Stepped Care Management of Low Back Pain in the Military Health System: A Trial Protocol. Pain Medicine. 2020;21, Issue Supplement_2;S73–S82.
Von Korff M. Studying the Natural History of Back Pain. Spine 1994;19(18):p 2041S-2046S.
Wahlgren DR, Atkinson JH, Epping-Jordan JE, et al: One-year follow-up of first onset low back pain. Pain 1997;73:213-221.
Lemeunier N, Leboeuf-Yde C, Gagey O. The natural course of low back pain: a systematic critical literature review. Chiropr Man Therap. 2012 Oct 17;20(1):33.
Chang AH, Almagor O, Lee JJ, Song J, Muhammad LN, Chmiel JS, Moisio KC, Sharma L. The Natural History of Knee Osteoarthritis Pain Experience and Risk Profiles. J Pain. 2023 Dec;24(12):2175-2185..