Insurance, DisabilitySocial SecurityUnited States Social Security AdministrationDisabled PersonsDisability EvaluationPensionsEligibility DeterminationRehabilitation, VocationalReturn to WorkInsurance BenefitsEmploymentSick LeaveIntellectual DisabilityDevelopmental DisabilitiesActivities of Daily LivingLearning DisordersDisabled ChildrenMentally Disabled PersonsTreatment OutcomePain MeasurementQuestionnairesSeverity of Illness IndexMobility LimitationUnited StatesInternational Classification of Functioning, Disability and HealthQuality of LifeLow Back PainFollow-Up StudiesChronic DiseaseMultiple SclerosisHealth StatusProspective StudiesVeterans Disability Claims