- Design
- Prospective cohort with 10-year mortality follow-up (Cox models)
- Population
- 52,789 adults aged 65 or older attending municipal health checks in Okayama City, Japan
- Primary outcome
- All-cause mortality by Kihon Checklist oral-function score (0 to 3)
- Effect
- Adjusted HR 1.09 (score 1), 1.26 (score 2), 1.49 (score 3; 95% CI 1.38 to 1.60)
This Japanese cohort followed 52,789 community-dwelling adults aged 65 or older who had municipal health checks in 2006 to 2007, with mortality follow-up to December 2016. The Kihon Checklist oral-function score counted three self-reported problems: difficulty chewing, difficulty swallowing and dry mouth.
Higher scores were linked to higher mortality in the fully adjusted model (n = 49,665): adjusted hazard ratios were 1.09 (95% CI 1.04 to 1.13) for a score of 1, 1.26 (1.20 to 1.32) for 2 and 1.49 (1.38 to 1.60) for 3. Chewing difficulty (aHR 1.19) and swallowing difficulty (1.18) were each independently linked to death, but dry mouth was not (1.02, 95% CI 0.98 to 1.06).
This shows that simple questions carry prognostic information. It does not show that treating oral problems would extend life, and frailty, nutrition and illness could account for part of the link.
- Ask older patients about chewing, swallowing and dry mouth as part of routine review.
- Treat chewing and swallowing difficulty as a prompt for dental, speech therapy and nutrition assessment.
- Do not read dry mouth alone as a mortality signal; it was not linked here.
- Consider these symptoms alongside weight loss and frailty screening.
Why it matters
Oral function is rarely assessed in routine care, yet a short self-report picked up a gradient in risk.
Don't overread it
Observational and Japanese; self-reported symptoms, and it does not show that improving oral function reduces mortality.
The statistics, in plain English
A hazard ratio of 1.49 for a score of 3 means about 49% higher rate of death over ten years than for those with no problems, after adjustment for other measured factors. It is an association; poor chewing may be a marker of frailty rather than a cause.
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