Parkinson's Disease in Nursing Homes

Prevalence of Parkinson's in Nursing Homes

• In 2016, a significant portion of nursing home residents had Parkinson's disease.
• Factors affecting prevalence:
  • Increased by:
    • Longer disease duration
    • In-migration of cases
    • Out-migration of healthy people
    • Improved diagnostics
    • Increase in new cases
  • Decreased by:
    • Shorter duration of disease
    • High-case fatality
    • Out-migration of cases
    • Improved cure rate of cases
    • Decrease in incidence (new cases)

Incidence vs. Proportion

• Incidence:
  • Frequency of new cases
  • Measures risk (as people in the denominator can be part of the numerator)
  • Quantifies the number of problems developing in a population at risk over time
  • Usually given as the number of cases
  • To calculate:
    • Number of people in the defined population
    • Number of people developing the condition in that time period
    • Specified time period
• Proportion:
  • Expresses counts with recognition that those people are part of a bigger population
  • Expressed as a percentage or rate

Rates and Burden of Disease

• Rates incorporate the time each person is at risk of an outcome.
• Burden of disease:
  • How a disease affects the quality of life of people
  • Impacted by:
    • Impairment: Any loss or abnormality of psychological or anatomic structure/function
    • Restriction: A result of an impairment, limiting task performance
    • Handicap: A disadvantage for an individual resulting from an impairment or disability
• Years of life lost due to death (YLL):
  • Takes someone's life expectancy to when they actually die
  • Influenced by factors like family history, money involved, and knowledge of the disease.

Bias in Studies

• Self-selection bias:
  • Non-representativeness of the target population due to self-selection.
• Healthy volunteer effect:
  • Needs to be considered in occupational studies.
• Allocation bias:
  • Introduced if the randomisation list is not concealed.
  • Randomisation is a two-step process:
    • Establishing the randomisation sequence
    • Protecting the sequence or allocation.
• Hawthorne effect:
  • People behave differently knowing they're in a study.
• Placebo effect:
  • People have different expectations knowing they're in a study or on a treatment.
• Attrition bias:
  • People leaving the study, and why they are leaving.
  • Overcome by intention-to-treat analysis.
• Detection bias:
  • Researchers or assessors may be aware of the treatment group, potentially influencing their observations.
  • Blinding researchers and assessors to avoid this bias is important.

Misclassification Bias

• Nondifferential Misclassification:
  • Errors occur equally in all groups being compared.
  • Leads to random error and instrument bias.
• Differential Misclassification:
  • Likely to occur in one group more than another due to systematic error, like recall, response, or observer bias.

Study Types

• Case series/study:
  • Describes characteristics of people with a specific disease and exposure.
• Cross-sectional study:
  • Measures prevalence, taking a snapshot in time.
  • Assesses exposures, outcomes, and health needs.
• Case-control study:
  • Compares cases (people with a disease) to controls without the disease.
  • Looks at previous risk factors.
• Cohort study:
  • Follows a group of people with a specific exposure over time, analyzing the outcome.
• Interventional study:
  • An intervention is given to a group of people, and the outcome is studied.
  • Randomization ensures equal chance of receiving intervention and similar characteristics in each group.
• Systematic review:
  • Identifies relevant studies on a topic, assesses their quality, synthesizes findings, and presents an impartial and unbiased summary.
  • Uses data from multiple studies with similar designs, providing a single summary result.
• Randomized controlled trial:
  • Experimental study design with an intervention and placebo/control.

Types of Causes

• Component cause:
  • A factor contributing to a disease.
• Sufficient cause:
  • A combination of components leading to the effect.

Types of Data

• Numerical:
  • Continuous: e.g., blood pressure.
  • Discrete: e.g., number of children.
• Categorical:
  • Nominal: e.g., blood type, hair color.
  • Ordinal: e.g., pain scale.

Data Collection Methods

• Observation:
  • The study setting can influence the results.
• Interviews:
  • Scheduled standardized interview: everyone is asked the same questions in a structured way.
  • Non-scheduled standardized interview: the same questions, but in a more relaxed manner.
  • Non-standardized interview: a conversation.
• Questionnaires:
  • Participants fill out the questionnaire themselves.
  • Include demographic questions to describe the sample and generalize results.

Question Types

• Open: allows for detailed data.
• Closed: allows for limited responses.
• Double-barreled: asks two questions in one.
• Leading: guides respondents in a specific direction.

Types of Scales

• Visual analog scale:
  • Measures intensity of a subjective experience with a line.
• Likert scale:
  • Measures agreement or disagreement with a series of statements.
• Semantic differential scale:
  • Measures attitudes and perceptions on a bipolar scale.

Significance

• Statistical significance:
  • If a result does not include 1 in its confidence interval.
• Clinical significance:
  • Whether the result is meaningful or impactful in a practical sense.

Mean Difference

• The absolute difference between means of two continuous variables.
• A mean difference of 0 indicates no effect.

P-value

• The probability that an event is due to chance.
• A lower p-value suggests a statistically significant result.

Disease Transmission

• Direct: Transmitted directly, e.g., through touch.
• Indirect:
  • Vehicle-borne: Transmitted through inanimate objects, e.g., contaminated food.
  • Vector-borne: Transmitted through animals, e.g., mosquito bites.
• Airborne:
  • Droplet: Larger particles from the respiratory tract, e.g., coughing or sneezing.
  • Dust: Smaller particles.