Despite a growing body of knowledge regarding essential tremor (ET), past studies have fallen short in capturing the full impact of ET on patients and caregivers. We propose enfeeblement (i.e., having the qualities of being prematurely old, helpless, or debilitated) as a novel clinical outcome measure in ET. Due to the lack of enfeeblement scales for ET in the literature, we developed and validated an enfeeblement scale for ET.
Methods:
The Essential Tremor Enfeeblement Survey (ETES) consists of eight 5-point Likert-type scale questions and is designed to be a caregiver-reported outcome.
Results:
Enfeeblement scores showed a floor effect of 15.3%, no ceiling effects, and demonstrated good overall test–retest reliability (intraclass correlation coefficient = 0.73), favorable internal consistency (Cronbach α coefficient = 0.92) and good convergent validity.
Conclusion:
The ETES has robust properties. Aside from future studies of enfeeblement in ET, enfeeblement should be explored more broadly as a psychometric measure across other neurological disorders.
LouisED.Non-motor symptoms in essential tremor: a review of the current data and state of the field. Parkinsonism Relat Disord. 2016;22(suppl 1):S115–S118.
2.
ChandranVPalPK. Essential tremor: beyond the motor features. Parkinsonism Relat Disord. 2012;18(5):407–413.
3.
KronenbuergerMKonczakJZieglerW. Balance and motor speech impairment in essential tremor. Cerebellum. 2009;8(3):389–398.
4.
ParisiSLHerouxMECulhamEGNormanKE. Functional mobility and postural control in essential tremor. Arch Phy Med Rehabil. 2006;87(10):1357–1364.
5.
LouisEDGerbinMGaleckiM. Essential tremor 10, 20, 30, 40: clinical snapshots of the disease by decade of duration. Eur J Neurol. 2013;20(6):949–954.
Bermejo-ParejaFLouisEDBenito-LeonJ. Risk of incident dementia in essential tremor: a population-based study. Mov Disord. 2007;22(11):1573–1580.
8.
ChunlingWZhengX. Review on clinical update of essential tremor. Neurol Sci. 2016;37(4):495–502.
9.
LouisED. Essential tremor as a neuropsychiatric disorder. J Neurol Sci. 2010;289(1-2):144–148.
10.
LeeSMKimMLeeHMKwonKYKohSB. Nonmotor symptoms in essential tremor: comparison with Parkinson’s disease and normal control. J Neurol Sci. 2015;349(1-2):168–173.
11.
GerbinMVinerASLouisED. Sleep in essential tremor: a comparison with normal controls and Parkinson’s disease patients. Parkinsonism Relat Disord. 2012;18(3):279–284.
12.
SengulYSengulHSYucekayaSK. Cognitive functions, fatigue, depression, anxiety, and sleep disturbances: assessment of nonmotor features in young patients with essential tremor. Acta Neurol Belg. 2014.
13.
LundervoldDAAmentPAHoltP. Social anxiety, tremor severity, and tremor disability: a search for clinically relevant measures. Psychiatry J. 2013;2013:257459.
14.
LouisEDRiosE. Embarrassment in essential tremor: prevalence, clinical correlates and therapeutic implications. Parkinsonism Relat Disord. 2009;15(7):535–538.
15.
LouisEDMachadoDG. Tremor-related quality of life: a comparison of essential tremor vs. Parkinson’s disease patients. Parkinsonism Relat Disord. 2015;21(7):729–735.
16.
HerouxMEParisiSLLarocerie-SalgadoJNormanKE. Upper-extremity disability in essential tremor. Arch Phys Med Rehabil. 2006;87(5):661–670.
17.
BainPGMallyJGrestyMFindleyLJ. Assessing the impact of essential tremor on upper limb function. J Neurol. 1993;241(1):54–61.
18.
LouisEDBarnesLAlbertSM. Correlates of functional disability in essential tremor. Mov Disord. 2001;16(5):914–920.
19.
MorganSKellnerSGutierrezJ. The experience of essential tremor caregivers: burden and its correlates. Front Neurol. 2017;8:396.
20.
KellnerSMorganSGutierrezJ. Perceived embarrassment and caregiver burden in essential tremor caregivers. J Neurol Sci. 2017;383:205–210.
21.
CloustonTS. Lecture VII. States of mental enfeeblement (dementia, amentia, psychoparesis, congenital imbecility, idiocy). Clinical Lectures on Mental Diseases. Philadelphia, PA: Henry C Lea’s Son & Co; 1884:204–216.
22.
CloustonTS. Conditions of Mental Enfeeblement. Hospital (Lond 1886). 1894;17(422):57.
23.
CloustonTS. The Incurable Mental Weakness Liable to Follow the Acute Unsoundnesses of Mind. Unsoundness of mind. London, Great Britain: Methuen & Co; 1911:189–193.
24.
CaslerL. A simple verbal procedure for reducing the rates of psychosomatic enfeeblement and death in an aged population. Death Studies. 1985;9(3-4):295–307.
25.
CalderwoodSKMurshidAPrinceT. The shock of aging: molecular chaperones and the heat shock response in longevity and aging—a mini-review. Gerontology. 2009;55(5):550–558.
26.
AgasDMarchettiLDouniESabbietiMG. The unbearable lightness of bone marrow homeostasis. Cytokine Growth Factor Rev. 2015;26(3):347–359.
27.
JoKHDoorenbosAZ. Understanding the meaning of human dignity in Korea: a content analysis. Int J Palliat Nurs. 2009;15(4):178–185.
28.
AguayoGADonneauAFVaillantMT. Agreement between 35 published Frailty Scores in the general population. Am J Epidemiol. 2017;186(4):420–434.
CollinsKRohlBMorganSHueyEDLouisEDCosentinoS. Mild cognitive impairment subtypes in a cohort of elderly essential tremor cases. J Int Neuropsychol Soc. 2017;23(5):390–399.
31.
LouisEDFordBBismuthB. Reliability between two observers using a protocol for diagnosing essential tremor. Mov Disord. 1998;13(2):287–293.
32.
LouisEDWendtKJAlbertSMPullmanSLYuQAndrewsH. Validity of a performance-based test of function in essential tremor. Arch Neurol. 1999;56(7):841–846.
33.
LouisEDOttmanRFordB. The Washington Heights-Inwood Genetic Study of Essential Tremor: methodologic issues in essential-tremor research. Neuroepidemiology. 1997;16(3):124–133.
34.
LouisEDBarnesLFWendtKJ. Validity and test-retest reliability of a disability questionnaire for essential tremor. Mov Disord. 2000;15(3):516–523.
35.
LouisEDGerbinMMullaneyMM. What is the functional significance of nondominant arm tremor in essential tremor?Mov Disord. 2010;25(15):2674–2678.
36.
FolsteinMFFolsteinSEMcHughPR. “Mini-mental state”. A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12(3):189–198.
37.
MarioniREChatfieldMBrayneCMatthewsFE; Medical Research Council Cognitive Function and Ageing Study Group. The reliability of assigning individuals to cognitive states using the Mini Mental-State Examination: a population-based prospective cohort study. BMC Med Res Methodol. 2011;11:127.
38.
NasreddineZSPhillipsNABedirianV. The Montreal Cognitive Assessment, MoCA: a brief screening tool for mild cognitive impairment. J Am Geriatr Soc. 2005;53(4):695–699.
39.
YesavageJABrinkTLRoseTL. Development and validation of a geriatric depression screening scale: a preliminary report. J Psychiatr Res. 1982–1983;17(1):37–49.
40.
SpitzerRLKroenkeKWilliamsJBLoweB. A brief measure for assessing generalized anxiety disorder: the GAD-7. Arch Intern Med. 2006;166(10):1092–1097.
41.
GrafC. The Lawton instrumental activities of daily living scale. Am J Nurs. 2008;108(4):52–62.
42.
MorrisJC. The Clinical Dementia Rating (CDR): current version and scoring rules. Neurology. 1993;43(11):2412–2414.
43.
WoolfCSlavinMJDraperB. Can the clinical dementia rating scale identify mild cognitive impairment and predict cognitive and functional decline?Dement Geriatr Cogn Disord. 2016;41(5-6):292–302.
44.
BurtonLJMazerolleSM. Survey instrument validity part I: principles of survey instrument development and validation in athletic training education research. Athl Train Educ J. 2011;6(1):27–35.
45.
TraubREGerbinMMullaneyMMLouisED. Development of an essential tremor embarrassment assessment. Parkinsonism Relat Disord. 2010;16(10):661–665.
46.
McHorneyCATarlovAR. Individual-patient monitoring in clinical practice: are available health status surveys adequate?Qual Life Res. 1995;4(4):293–307.
47.
Martinez-MartinPJimenez-JimenezFJCarroza GarciaE. Most of the Quality of Life in Essential Tremor Questionnaire (QUEST) psychometric properties resulted in satisfactory values. J Clin Epidemiol. 2010;63(7):767–773.
48.
HallgrenKA.Computing inter-rater reliability for observational data: an overview and tutorial. Tutor Quant Methods Psychol. 2012;8(1):23–34.
49.
BarryJAMollanSBurdonMAJenkinsMDennistonAK. Development and validation of a questionnaire assessing the quality of life impact of Colour Blindness (CBQoL). BMC Ophthalmol. 2017;17(1):179.
50.
TavakolMDennickR. Making sense of Cronbach’s alpha. Int J Med Educ. 2011;2:53–55.
51.
StreinerDL. Starting at the beginning: an introduction to coefficient alpha and internal consistency. J Pers Assess. 2003;80(1):99–103.
52.
Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims Food and Drug Administration, 2009. US Food and Drug Administration. Guidance for industry: patient-reported outcome measures: use in medical product development to support labeling claims. Food and Drug Administration. https://www.fda.gov/downloads/drugs/guidances/ucm193282.pdf.
