Older Women and Recurrent TB Face Higher Risk of Bone and Joint Tuberculosis, Study Finds

Tuberculosis is best known as a lung disease, but the bacterium responsible, Mycobacterium tuberculosis, can escape the airways and settle almost anywhere in the body. One of its stealthiest destinations is the skeleton. Osteoarticular tuberculosis, or OATB, invades bones, joints, and the spine, where it can quietly erode vertebrae and degrade cartilage for months before anyone suspects the true cause. A new hospital-based study from Shanghai now offers some of the clearest population-level numbers yet on who develops this form of the disease and how much it shortens lives, and the findings carry an uncomfortable message for older patients with diabetes.

Researchers at Shanghai Pulmonary Hospital, a tertiary referral center for tuberculosis affiliated with Tongji University, mined seven years of patient records from the Infectious Disease Reporting Information System maintained by the Chinese Center for Disease Control and Prevention. Between January 2014 and December 2020, they identified 452 patients with confirmed OATB among more than 17,000 tuberculosis patients treated at the center. Using simple random sampling, they selected 1,168 tuberculosis patients without bone or joint involvement as controls, then applied univariate and multivariate logistic regression to isolate the factors that genuinely distinguish OATB cases from ordinary pulmonary disease.

The statistical machinery behind the study is worth unpacking, because it determines how much confidence the conclusions deserve. Logistic regression estimates an odds ratio for each candidate risk factor, expressing how the odds of developing OATB multiply when that factor is present, while holding every other measured variable constant. The team also computed the area under the curve, or AUC, a number between 0.5 and 1.0 that quantifies how well a given threshold separates cases from controls. An AUC of 0.5 is equivalent to a coin flip; values above 0.7 are generally considered acceptable discrimination for a clinical screening rule.

Three independent risk factors emerged. Female sex, older age, and a history of recurrent tuberculosis each raised the odds of OATB after adjustment, meaning these associations persisted even when the analysis accounted for all other measured characteristics. The age effect proved strong enough to generate a usable screening threshold: at 52.5 years, age alone predicted OATB with an AUC of 0.764, respectable discrimination for a single demographic variable. The authors suggest that clinicians in settings with adequate diagnostic resources may consider routine bone and joint screening for tuberculosis patients above this cutoff, though they caution that the threshold must be validated in diverse populations before it becomes standard practice.

One result stands out for its counterintuitive direction. Drug resistance was inversely associated with OATB, meaning patients with drug-resistant tuberculosis were less likely to have bone and joint involvement. The authors do not overinterpret this finding, but it hints at a biological or epidemiological distinction between the strains or patient populations that seed the skeleton and those that drive multidrug-resistant pulmonary epidemics. Understanding why drug-sensitive and drug-resistant disease behave differently in bone could eventually illuminate the mechanisms by which the bacillus establishes itself in skeletal tissue.

The prognosis analysis is where the study turns grim. Using Cox regression, a technique that models the hazard ratio, or HR, to express how a factor multiplies the instantaneous risk of death over follow-up time, the researchers found that OATB itself predicted mortality. Patients with bone and joint tuberculosis died at roughly 2.3 times the rate of comparable patients without skeletal disease, an HR of 2.342. This is not merely a marker of advanced disease; extrapulmonary spread appears to be an independent predictor of poor outcome in its own right.

Diabetes made everything worse. Among OATB patients, those with diabetes faced a hazard ratio of 3.877 for death, nearly four times the mortality risk of their non-diabetic counterparts. The interaction is biologically plausible. Diabetes impairs cell-mediated immunity, the very arm of the immune system that contains Mycobacterium tuberculosis inside macrophages and granulomas. Hyperglycemia also disrupts neutrophil function and wound healing, which matters enormously when the infection is destroying bone and joint architecture. In a country where more than 100 million adults live with diabetes, the combination of metabolic disease and skeletal tuberculosis represents a formidable public health challenge.

The clinical implications follow directly from the numbers. Older, female, and recurrent tuberculosis patients carry higher OATB risk and may benefit from heightened clinical suspicion, particularly when they present with unexplained joint pain, spinal deformity, or chronic draining sinuses. Because OATB often mimics more common conditions such as degenerative arthritis, osteoporotic fractures, or even bone tumors, diagnosis is frequently delayed until irreversible damage has occurred. The study’s finding that age above 52.5 years discriminates reasonably well between cases and controls gives clinicians a concrete, evidence-based trigger for considering imaging of bones and joints in tuberculosis patients, rather than relying on intuition alone.

Public health planners may find the mortality data even more consequential than the risk factors. If OATB roughly doubles mortality and diabetes nearly quadruples it among affected patients, then identifying skeletal involvement early is not just a matter of preserving mobility; it is a matter of survival. The authors argue that OATB predicts poorer prognosis, especially with diabetes, and therefore requires intensified public health and clinical management. In practical terms, that could mean integrating bone and joint evaluation into routine tuberculosis care for older patients, screening diabetic tuberculosis patients more aggressively for extrapulmonary disease, and ensuring that treatment regimens account for the longer courses and surgical interventions often needed for skeletal infection.

The study, published in BMC Infectious Diseases, was funded by the Shanghai Clinical Research Center for Infectious Disease (Tuberculosis) and approved by the ethics committee of Shanghai Pulmonary Hospital. Its retrospective, anonymized design allowed the researchers to leverage seven years of real-world surveillance data without burdening patients, but it also means the findings reflect a single tertiary referral center in Shanghai. Whether the 52.5-year threshold and the magnitude of the diabetes effect hold in other populations, with different diabetes prevalence, nutritional status, and strain diversity, remains an open question the authors themselves flag. Still, for a disease that has lurked in the shadows of tuberculosis epidemiology, the study delivers something rare: hard numbers on who is at risk, and how much that risk costs in lives.

Subject of Research: Tuberculosis

Article Title: Risk and prognosis analysis of osteoarticular tuberculosis in tuberculosis patients

Article References: Fang, Y., Wang, Y.-W., Yan, L.-P., Liang, L., Zhou, Q.-Q., Liu, L.-R., Liu, Z.-H., & You, X.-F. (2026). Risk and prognosis analysis of osteoarticular tuberculosis in tuberculosis patients. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14370-8

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14370-8

Keywords: tuberculosis, osteoarticular tuberculosis, risk factors, prognosis, diabetes, epidemiology, Risk, analysis, osteoarticular, patients, scientific research