There are multiple definitions:

1. Nepean dyspepsia index(English)

   • designed to measure impairment of a subject's ability to engage in relevant aspects of their life and also their enjoyment of these aspects
   • FD, LDQ
   • Gastroenterology, Quality of life
   • https://doi.org…36.1999.00445.x
   • https://doi.org…000000000001314

2. nephrogenic diabetes insipidus(English)

   • Nephrology, Diabetes

3. neck disability index(English)

   • ACDF, AE, CAC, CDA, DASH, dCSA, DDD, FDA, INIT, MET, ROM, FSN, FSU, HO, HPD, IDE, LP, MCS, NRS, SAMP, SCS, SSPT, PCS, SF-36, TrP, ULD, VAS
   • Disability, Physical therapy, Spine (or spinal cord)
   • https://doi.org…X12595770849605
   • https://doi.org…ksp.2021.102428
   • https://doi.org…6.10.SPINE16264

4. neurodevelopmental impairment(English)

   • moderate to severe neurologic disability defined by 1 or more of the following: moderate to severe motor impairment (CP or non-CP) with a GMFCS level ≥2, a BSID III cognitive score of <70, severe visual impairment (bilateral blindness with vision <20/200), or severe hearing impairment (HI) (permanent hearing loss that interferes with ability to understand or communicate with or without amplification)
   • BSID, CP, GMFCS
   • Neuropathy, Embryology /reproduction
   • https://dx.doi.…/peds.2017-3091

5. node dissociation index(English)

   • a graph measure to calculate changes in connectivity profile of cortical networks
   • ADHD, fMRI
   • Neural network, Brain (dys)function
   • https://doi.org…3/cercor/bhw209

6. National Death Index(English)

   • connects public health and medical researchers with U.S. death records
   • ACS, CDC, NHANES, NSTEMI, PCI, PD, STEMI, UA
   • Epidemiology, Statistics, Parkinson, Public Health
   • https://doi.org…/ehjqcco/qcy009
   • https://doi.org…877-024-05000-6
   • https://www.cdc…/ndi/index.html