Basic Epidemiology for Tuberculosis Program Staff 2nd Edition Reported TB Cases United States 30,000 25,000 s e s 20,000 a C f o 15,000 . o N 10,000 5,000 0 Basic Epidemiology for Tuberculosis Program Staff 2nd Edition Marian Passannante, PhD Associate Professor, New Jersey Medical School & School of Public Health Epidemiologist, New Jersey Medical School Global TB Institute University of Medicine and Dentistry of New Jersey Newark, New Jersey Anna Sevilla, MPH, MBS Research Coordinator New Jersey Medical School Global TB Institute University of Medicine and Dentistry of New Jersey Newark, New Jersey Nisha Ahamed, MPH Program Director, Education and Training New Jersey Medical School Global TB Institute University of Medicine and Dentistry of New Jersey Newark, New Jersey This product is funded by the Centers for Disease Control and Prevention, Division of Tuberculosis Elimination i Acknowledgments We wish to thank the following individuals and groups who participated in drafting and reviewing this guide: Rajita Bhavaraju, MPH, CHES Ann Hinds, BS, RN Eileen Napolitano, BA Johnson County Health System, Kansas Lillian Pirog, RN, PNP Mark Wolman, MA, MPH Mary McKenzie, EdM, MS, RN NJMS-Global Tuberculosis Institute City of Chelsea, Massachusetts Health Dept. Kathryn Arden, MD, MHA South Carolina Dept. of Health and Darlene Morse, RN, MEd, CHES, CIC Environmental Control New Hampshire Dept. of Health and Human Services Nancy Baruch, RN, MBA Anna Lee, BS Eyal Orel, MS, PhD Maryland Dept. of Health and Seattle & King County Public Health TB Mental Hygiene Control Program Jason Cummins, MPH Kristina Schaller, BS Trudy Stein-Hart, MS Arizona Dept. of Health Services Tennessee Department of Health Mary Katie Sisk, RN, CIC Michele Dincher, RN, BSN District of Columbia Dept. of Health Lisa Paulos, RN, MPH Pennsylvania Dept. of Health Sarah Solarz, BA, MPH Minnesota Department of Health Nicole Evert, MS Patricia Thickstun, PhD Roque Miramontes, PA-C, MPH Ann Tyree, MS Lori Armstrong, PhD Texas Dept. of State Health Services Juliana Grant, MD, MPH Maryam Haddad, MSN, MPH Jennifer Grinsdale, MPH Kai Young, MPH San Francisco Dept. of Public Health Division of Tuberculosis Elimination Centers for Disease Control and Ellen Hill, MS, DLSHTM Prevention Idaho Dept. of Health and Welfare ii Previous Edition – 2005 Reviewers Donna Allis, PhD, RN Diane McCracken, RN Joanne Becker Eileen Napolitano, BA Rajita Bhavaraju, MPH, CHES Stephanie Napolitano, MPH Beverly Ann Collins, RN, MS, CIC Thomas Navin, MD Denise Cory Margaret Osborn, RN, BSN Myrene Couves Bob Parker, MS Pete Denkowski Thomas Privett Patsy Eddington Nandini Selvam, PhD, MPH Kim Field, RN, MSN Mary Spinner, RN, BSN Vipra Ghimire, MPH, CHES Marie Villa, RN Chris Hayden, BA Linda Weldon, RN, BSN Bart Holland, PhD, MPH Diane Werling Natalia Kurepina, PhD Mark Wolman, MA, MPH Kayla Laserson, ScD Oralia Zamora, RN Prepared by: Marian Passannante, PhD, and Nisha Ahamed, MPH, CHES All material in this document is in the public domain, except where noted “Reprinted here with permission.” All material in the public domain may be used and reprinted without special permission; citation of source, however, is appreciated. Suggested citation: New Jersey Medical School Global Tuberculosis Institute. Basic Epidemiology for Tuberculosis Program Staff, 2nd Edition. 2012: (inclusive pages) The New Jersey Medical School Global Tuberculosis Institute is a TB Regional Training and Medical Consultation Center (RTMCC) funded by the Centers for Disease Control and Prevention, Division of Tuberculosis Elimination. Graphic Design: DeeDee Hamm iii iv Table of Contents Part One: The Basics 1. Introduction – Uses of Epidemiology in Tuberculosis Control ............................................................................................ 1 2. What Is Epidemiology? ................................................................... 3 3. Types of Epidemiology .................................................................... 4 A. Descriptive Epidemiology ......................................................4 i. Public Health Surveillance ......................................................4 ii. Descriptive Epidemiology Using TB Surveillance Data ............6 iii. Using TB Surveillance Data for Program Evaluation ...............9 iv Accessing Data Online ........................................................11 B. Analytic Epidemiology ..........................................................12 4. Key Concepts in Epidemiology ..................................................... 13 A. Morbidity .............................................................................13 i. Incidence ............................................................................14 ii. Prevalence ..........................................................................16 iii. Comparison of Incidence and Prevalence .............................17 iv. Sample Calculations: Incidence and Prevalence ...................19 B. Mortality ..............................................................................21 i. Measures of Mortality .........................................................21 ii. Sample Calculation of Crude and Age-Specific Mortality Rates ...................................................................................22 iii. Age-Adjusted Rates ............................................................24 iv. Case-Fatality Rate ...............................................................26 v. Cause-Specific Mortality Rate ..............................................29 5. Presenting TB Program Data ...................................................... 32 A. Measurement Scales .............................................................32 B. Summarizing the Data ..........................................................32 i. The Middle Values...............................................................33 ii. Variation .............................................................................34 iii. Which Measures to Use? .....................................................37 C. Presenting Data ....................................................................39 i. Bar Charts or Graphs and Pie Charts ....................................39 ii. Histograms ..........................................................................42 v Part Two: Beyond the Basics 6. Measuring Test Validity ................................................................ 46 A. Sensitivity, Specificity and Predictive Values .........................46 B. Test Validity Examples ..........................................................48 7. Study Designs ............................................................................... 53 A. Cross-Sectional Studies ........................................................53 B. Case-Control Studies ............................................................54 i. Odds Ratios ........................................................................55 ii. Sample Calculation: Odds Ratio ..........................................55 C. Cohort Studies .....................................................................56 i. Relative Risk ........................................................................57 ii. Sample Calculation: Relative Risk ........................................59 D. Clinical Trials .........................................................................60 8. Statistical Concepts Used in Epidemiologic Studies ................... 63 A. P-Values ................................................................................63 B. Confidence Intervals .............................................................64 C. Confounding Factors ............................................................66 D. Bias ......................................................................................67 E. Meta-analysis .......................................................................68 9. Molecular Epidemiology: Genotyping and TB Control ............... 70 A. What Is TB Genotyping? .......................................................70 B. National TB Genotyping Service and the TB Genotyping Information Management System .....................71 C. Using TB Genotyping in TB Outbreak Detection ...................72 D. Cluster Investigations ...........................................................73 Part Three: Putting It All Together 10. TB Case Study .............................................................................. 75 A. How to Use TB Surveillance Data in TB Control ....................75 B. How to Use TB Surveillance Data in TB Control Answer Key ..........................................................................83 Appendix I – Common Statistical Terms Used in Epidemiology .... 87 Appendix II – RVCT Form: Report of Verified Case of Tuberculosis .................................................................................... 101 Appendix III – National TB Program Objectives .......................... 107 Appendix IV – National Tuberculosis Indicators Project (NTIP) ............................................................................................. 111 Appendix V – Solutions for Sample Problems .............................. 115 Appendix VI – Suggested Reading List .......................................... 117 vi Part One: The Basics 1. Introduction – Uses of Epidemiology in Tuberculosis Control Prevention and control of tuberculosis (TB) in the United States is an important public health responsibility. Effective