Related Experiment Video
Updated: Mar 13, 2026
Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
Published on: March 4, 2014
Increased Incidence of Amyotrophic Lateral Sclerosis in Polymyositis: A Nationwide Cohort Study
Chia-Chun Tseng1, Shun-Jen Chang2, Wen-Chan Tsai3
1Kaohsiung Municipal Ta-Tung Hospital, Kaohsiung, Taiwan.
Objective:
Past studies have shown common pathologic characteristics and shared immunologic features between polymyositis (PM) and amyotrophic lateral sclerosis (ALS). To explore the potential relationship between the 2 diseases, we performed a nationwide cohort study.
Methods:
We identified all newly diagnosed patients with PM from Taiwan's Registry of Catastrophic Illness Database between January 1, 1998 and December 31, 2011. Each PM patient was matched to ≤5 control patients from the National Health Insurance Research Database by sex, age, and entry date. Cumulative incidence of ALS was calculated by the Kaplan-Meier method and compared using the log rank test. Cox hazard regression was used to calculate the hazard ratio of ALS.
Results:
A total of 1,778 PM patients and 8,124 control patients were enrolled. PM patients had a higher cumulative incidence of ALS (P < 0.001). There was a positive correlation in being diagnosed with ALS in patients previously diagnosed with PM when stratified by sex. Consistent trends were conserved across different age strata. The strength of this association remained statistically significant after adjusting for sex, age, and concomitant autoimmune diseases (hazard ratio 25.72 [95% confidence interval 2.95-224.58]; P = 0.003).
Conclusion:
This study demonstrates that a diagnosis of PM increased the likelihood of a subsequent ALS diagnosis, independent of sex, age, and concomitant autoimmune diseases. Future studies are warranted to clarify the underlying biologic mechanisms and to translate them into clinical therapeutic options.
Insights
Patients diagnosed with polymyositis (PM) have a significantly higher risk of developing amyotrophic lateral sclerosis (ALS). This association persists regardless of age, sex, or other autoimmune conditions.
Area of Science:
- Neurology
- Immunology
- Epidemiology
Background:
- Polymyositis (PM) and amyotrophic lateral sclerosis (ALS) share pathological and immunological characteristics.
- Previous research suggests potential links between these two distinct neurological and autoimmune conditions.
Purpose of the Study:
- To investigate the potential association between a polymyositis diagnosis and the subsequent risk of developing amyotrophic lateral sclerosis.
- To explore if this association is influenced by demographic factors or co-occurring autoimmune diseases.
Main Methods:
- A nationwide cohort study was conducted using Taiwan's health databases.
- Patients with newly diagnosed polymyositis (PM) were identified and matched with control individuals.
- Cumulative incidence and hazard ratios for amyotrophic lateral sclerosis (ALS) were calculated using Kaplan-Meier and Cox regression analyses.
Main Results:
- The study identified 1,778 PM patients and 8,124 controls.
- Polymyositis patients exhibited a significantly higher cumulative incidence of ALS (P < 0.001).
- A diagnosis of PM substantially increased the hazard of subsequent ALS diagnosis (HR 25.72), independent of sex, age, and other autoimmune diseases.
Conclusions:
- A polymyositis diagnosis is a significant risk factor for developing amyotrophic lateral sclerosis.
- The observed association is robust across different demographics and clinical contexts.
- Further research is needed to elucidate the biological mechanisms and potential therapeutic targets.
