Saving Time, Money, and Work: How to Do Secondary Data Analysis Vijay Singh, MD, MPH, MS, University of Michigan Arch Mainous III, PhD, Medical University of South Carolina Andrew Coco, MD, MS, Lancaster General Hospital Andrew Bazemore, MD, MPH, Robert Graham Center

Learning objectives Understand practical aspects of performing secondary data analysis Review steps in analyzing secondary data 2

Outline Define secondary data analysis Examine questions secondary data can answer Discuss advantages and disadvantages of secondary data analysis Mainous AG, Hueston WJ. Using other people’s data: the ins and outs of secondary data analysis. Fam Med 1997;29(8):

Outline Review steps to prepare data for analysis Describe sources of data Address how questions can be answered Discuss examples of secondary data analysis Mainous AG, Hueston WJ. Using other people’s data: the ins and outs of secondary data analysis. Fam Med 1997;29(8):

Define secondary data analysis Analysis of existing data that presents results or conclusions different from original report Data from: questionnaires, financial records, admitting and discharge forms, diagnostic and procedural data 5

Types of questions secondary data can answer Questions can be clinical, epidemiological, or health services research Researchers should conceptualize questions with data limitations in mind 6

Advantages of secondary data analysis Less time than primary data collection – You can access data that took months or years to collect Analysis can serve as pilot study – Find questions for primary data collection – Many grant proposals require preliminary data 7

Advantages of secondary data analysis Inexpensive compared to primary data collection – There may be no fee to access data – Personnel may be statistician or investigator only, if sufficient analytic skill 8

Disadvantages of secondary data analysis Dependent on data owner’s decisions on study population and measures used – Accept limitations or not use that data set Measures used are only ones available in secondary study – Measures may not be adequate or sufficient to answer question 9

Limiting factors in secondary data analysis Does type and source of data fit question? Does data owner allow others to analyze data? Example: Claims data allow analysis of health care use, but most claims data sets don’t have clinical information to adjust severity of illness 10

Steps in preparing data for analysis Review literature on topic of interest Identify a research question and database that allows investigation – May identify database first, then generate question based on available data 11

Steps in preparing data for analysis Choose measures available and decide if appropriate Decide if sample size is appropriate 12

Questions about data Can you get access to the data? – Some datasets require an application before you can receive the data Is data available in suitable format? – Some data elements may be available only in paper records, not in electronic database – Find out if you can access online the data, variable codebook, and data collection methods 13

Questions about data Does data contain information needed to answer question? Codebook or prior study can alert you to what data is available Can data be analyzed on investigator’s computer? – Need compatible software between database and investigator’s computer 14

Questions about data Is the data clean? – Evaluate for out-of-range data Example: Medicare data would have majority older than age 65 – Validate data with known values or relationships Example: Medicaid state data would have 10% of physician specialty as family medicine 15

Sources of data: administrative Databases of claims to 3 rd -party payers can address financing, practice patterns, utilization, and quality Medicare Medicaid

Sources of data: EMR Electronic medical records (EMR) – Compared to administrative data, EMR may have greater level of detail for individual patient visits – If you work in a group practice with EMR, contact your local information technology personnel to explore what data is available for further analysis 17

Sources of data: survey National Center for Health Statistics (NCHS) – Datasets, codebooks and questionnaires are free and downloadable through CDC – Many of these surveys use complex sampling designs that create nationally representative data May need biostatistician consultation to apply survey weights 18

NCHS surveys National Health Interview Survey (NHIS) – Addresses health conditions, insurance coverage, health behaviors National Health and Nutrition Examination Survey (NHANES) – Includes interviews, physical examinations, and laboratory tests National Ambulatory Medical Care Survey (NAMCS) – Assesses outpatient visits 19

20

Sources of data: survey Inter-University Consortium for Political and Social Research – Has thematic focus on aging, demographics, education, and physical and mental health – Allows search for variables across all datasets, online data analysis, and free dataset downloads to members of 700 institutions 21

22

Sources of data: surveys Society of General Internal Medicine Research Dataset Compendium – Gives description and expert evaluations of nearly 50 datasets, including medical education topics Council of Academic Family Medicine (CAFM) Educational Research Alliance (CERA) – Will begin annual surveys on medical education 23

24

25

Tips before obtaining data Talk with those already used data – They can provide invaluable advice Discuss research questions with the data owner – You should suggest possible outcomes to proposed research 26

How questions can be answered Consultation: Researchers at your home institution or program STFM Research Committee NAPCRG Consultants Directory

Example of analyzing a secondary dataset Steps in preparing data for analysis – Review literature on topic of interest – Identify a research question and database – Choose measures available and decide if appropriate – Talk with those already used data and data owner 28

Review literature on topic of interest Intimate partner violence (IPV): Most research is on victimization Few studies on IPV aggression or perpetration Little is known about health service use or physical health conditions of IPV aggressors 29

Identify a research question What is the prevalence of IPV aggression? What are the health service use and physical health conditions of IPV aggressors? 30

Identify a database Discussed with mentors National Comorbidity Survey-Replication (NCS-R) – Nationally-representative sample of over 10,000 U.S. adults – Public-use, data available only through ICPSR – My home institution is part of ICPSR, so data is free for download – Dataset available in STATA format, my statistical program 31

32

Choose measures available and decide if appropriate IPV aggression measured through widely-used questions Aggression limited to physical abuse in NCS-R Health services and physical health condition measures are limited but present 33

Talk with those already used data and data owner Research colleague had recently analyzed NCS-R and could explain complex survey design weighting ICPSR offered class on analyzing NCS-R Spoke with NCS-R principle investigator and project managers regarding measures 34

35

36

Questions? What research questions are you thinking about? What databases have you used, or are thinking of using? What secondary data analysis projects have you completed or have in-progress? 37