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How to use data to get “The Right Answer”

How to use data to get “The Right Answer”. Donna Spiegelman Departments of Epidemiology and Biostatistics Harvard School of Public Health stdls@channing.harvard.edu. Triumphs of Modern Epidemiology. Alcohol and esophageal cancer Hep B virus and liver cancer HPV and cervical cancer

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How to use data to get “The Right Answer”

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  1. How to use data to get“The Right Answer” Donna Spiegelman Departments of Epidemiology and Biostatistics Harvard School of Public Health stdls@channing.harvard.edu

  2. Triumphs of Modern Epidemiology • Alcohol and esophageal cancer • Hep B virus and liver cancer • HPV and cervical cancer • H. pylori and peptic ulcer • Folic acid and neural tube defects • Asbestos and lung cancer, mesothelioma • Aniline dye and bladder cancer • Vinyl chloride and angiosarcoma of the liver • Nickel and nasal cancer • Radon and lung cancer * • Aspirin and MI • Dalkon Shield IUD and PID ... www.epimonitor.net/EpiMonday/Triumph62501.htm http://www-cie.iarc.fr/monoeval/crthgr01.html

  3. The Start of Junk Science?? Definition of junk science: “It is a hodgepodge of biased data, spurious inference, and logical legerdemain, patched together by researchers whose enthusiasm for discovery and diagnosis far outstrips their dredging, wishful thinking, truculent dogmatism, and, now and again, outright fraud.”

  4. The Junkyard Dogs “Unfortunately, and increasingly today, one can find examples of junk science that compromise the integrity of the field of science and, at the same time, create a scare environment where unnecessary regulations on industry in particular, are rammed through without respect to rhyme, reason, effect or cause.” —Michael A. Miles, former CEO of the Phillip Morris tobacco company

  5. More controversial: “weak effects” • Air pollution and all-cause mortality, CVD mortality • Low dose exposure to radon and lung cancer • Low dose exposure to lead and neurotoxicity in children • Passive cigarette smoking and lung cancer • Alcohol and breast cancer • Oral contraceptives and breast cancer

  6. Population Attributable Risk and Weak Effects: Still Important!

  7. The research (and the researcher) that Philip Morris did not want you to see (Ragnar) Rylander was at that time at another Swedish university and had previously undertaken assignments for both Lorillard (another tobacco company) and Philip Morris. He was to be “officially … carried on the books as a consultant to FTR [Fabriques de tabac réunies, a Philip Morris subsidiary] and would be paid by FTR”. By means of material from internal industry documents it can be revealed that one company, Philip Morris, acquired a research facility, INBIFO, in Germany and created a complex mechanism seeking to ensure that the work done in the facility could not be linked to Philip Morris. In particular it involved the appointment of a Swedish professor as a ‘co-ordinator’, who would synthesise reports for onward transmission to the USA. Various arrangements were made to conceal this process Relation between Philip Morris and INBIFO Source: Diethelm et al. Lancet 2005

  8. Rylander “Studies … a relation between exposure to environmental tobacco smoke and lung cancer must take into account other …factors and the possibility that exposure to environmental tobacco smoke may be confounded. This has not been considered in the majority of such studies. Until this has been done, the claim of causality between environmental tobacco smoke and lung cancer remains uncertain.” Angell “There is no question that epidemiologic studies of risk factors for disease are of growing interest and importance, both for individuals and for the public health. It is important, however, to remember the pitfalls in interpreting them and to be cautious in advising patients on the basis of single or conflicting studies. This is particularly true of studies that purport to show only weak associations between exposures and disease.” “Weak Associations” (NEJM 1990)

  9. RCTs vs. observational studies • ß-carotene and lung cancer • HRT and CVD incidence and mortality • VIOXX • Dietary fat and breast cancer

  10. - Standard designs & analysis sometimes not adequately controlling for - confounding - information bias - selection bias Wrong answer? - Agreed: We can be doing a better job - Not agreed: HOW

  11. Confounding What do we do? “industry standard” END of mainstream epi methods collect data on known & suspected time-varying confounders MSMs, G-causal algorithm

  12. Confounding – outstanding problems • unmeasured confounding • known or suspected confounders • unknown confounders Fact: ~ 47% of US breast cancer incidence explained by known risk factors (Madigan et al., JNCI, 1987:1681-1695) r2 in most epi regressions (blood pressure, serum hormones) 20%-40% (Pediatric Task Force on BP Control in Children, Pediatrics, 2004; Hankinson, personal communication) Undiscovered genes? Unimagined environmental factors? Complex non-linear interactions?

  13. Solution to confounding by unknown risk factors: randomization VERY limited applicability Outstanding questions: a few strong risk factors or many weak ones? many rare ones or a few common ones? modeling of scenarios: do biases cancel? NEW IDEAS NEEDED

  14. Effects of unknown confounders References “The impact of residual and unmeasured confounding in epidemiological studies: a simulation study”, Davey-Smith and colleagues, Am J Epidemiol 2007; 166:646-655 “Poppers, Kaposi’s sarcoma, and HIV infection: empirical evidence of a strong confounding effect?”, Morabia, Prev Med 1995; 24:90-95. Marshall and Hastrup, Am J Epidemiol, 1999; 150:88-96, 1996; 143: 1069-1078

  15. Unmeasured confounding by known or suspected risk factors: We can use the data to get ‘the right answer’/’improve the validity of new studies’! Design: two-stage (Reilly & Salim, http://meb.ki.se/~marrei/software/) Stage 1 (Di, Ei, C1i), i = 1, . . . , n Stage 2 (Di, Ei, C1i, C2i), i = 1, . . . , n2 or (Ei, C1i, C2i), i = 1, . . . , n2 So that (Di, Ei, C1i, . ), i = n2+ 1, . . . , n1 + n2 n1 >> n2 Analysis: MLE of 2-stage likelihood References: Reilly M, 1996; Weinberg & Wacholder, 1990; Zhao & Lipsitz, 1992; Robins et al., 1994; + many others Cain & Breslow, AJE, 1988

  16. f (D | E, C1, C2; β) pdf of complete data Pr (I | D, E, C1), I = 1 if in stage 2, 0 otherwise f (D, I | E, C1; β,θ) = Pr (I | D, E, C1) f (D | E, C1, c2) f (c2 | E, C1) d c2 likelihood of 2-stage design = Stage 1 log [f (D | E, C1; , θ)] Stage 2 +log [f (D | E, C1,C2; )] Stage 2 + log [f (C2 | E, C1; θ ]

  17. Example: Kyle Steenland – retrospective cohort study of lung cancer in (Steenland & Greenland, AJE 2004;160:384-392) f (D | E, C); E = silica, C = smoking f (D | E) = f (D | E, C = s) Pr (C = s | E) Pr (C = s| E=r) = where relation to occupational silica exposure n1 silica workers in retrospective cohort study n2 silica workers in 1987 smoking prevalence study n3 NHIS participants on general population smoking rates in 1986 n4 ACS prospective cohort data on smoking & lung cancer Likelihood (silica + 1987 smoking data + US smoking data + ACS lung cancer & smoking data) silica 1987 silica smoking data = log [f(Di | Ei)] + ACS U.S r=1,…, R levels of exposure s=1,…, S levels of smoking could treat as known • assume distribution of smoking during entire period ~ 1987 distribution

  18. Obstacles: software? Design software available; Offsets or weights in PROC GENMOD or PROC PHREG can be used for analysis training? funding? Result: The right answer? A better answer? Is it worth it?

  19. INFORMATION BIAS: What do we usually do? NOTHING! What can we do? DesignAnalysis main study/validation study measurement error methods MS/EVS, MS/IVS, IVS misclassification methods References: Carroll, Ruppert, Stefanski, 1995, Chapman + Hall Rosner et al., AJE, 1990, 1992 Spiegelman, “Reliability studies” “Validation studies” Robins et al., JASA, 1994 Encyclopedia of Biostatistics

  20. EXAMPLE FRAMINGHAM HEART STUDY MAIN STUDY - 1731 men free of CHD (non-fatal MI, fatal CHD) At exam 4 - Followed for 10 years for CHD Incidence (163 events, cumulative incidence = 9.4%) REPRODUCIBILITY STUDY - 1346 men with all risk factors information at exams 2+3 (subgroup of 1731 men) -Risk factors in main study: Age, BMI, Serum Cholesterol, Serum Glucose, Smoking, SBP - Risk factors in reproducibility study: Serum Cholesterol, BMI, Serum Glucose, SBP, Smoking    

  21. Example: (from Rosner, Spiegelman, Willett; AJE, 1992) Framingham Heart Study Reliability study: (n = 1346 men) Subject i’s observed valve at time j Subject i’s true mean Reliability Coefficients CHOL 75% GLUC 52% BMI 95% SBP 72%

  22. Assumptions 1. Measurement error model within between 2. Disease incidence model log 3. • Pr (Di) is small • Measurement error independent of disease status 4. Reliability substudy “representative” of main study

  23. The Procedure ― For one variable measured with unbiased, additive error , where {simplest case} Step 1. Run a logistic regression of D on Z, U in main study logit Measured with Measured without error error (>1)

  24. Step 2. Estimate reliability coefficient from reliability substudy (n2 subjects, r replicates) Need same # of replicates per subject where TOTAL within-person variance (estimated)

  25. Step 3. Correct. corrected uncorrected MAIN STUDY RELIABILITY STUDY This contributes much less. (Donner, Intl Stat Review, 1986) 95% C.I. for odds ratio: = biological meaningful comparison, e.g. 90% percentile – 10% percentile

  26. 10-year cumulative incidence of CHD (163 events / 1731 men) Results: ^ 2.91 (1.62, 5.24) CHOL 2.21 (1343, 3.39) = 100mg/dl 1.75 (0.87, 3.52) GLUC 1.27 (0.97, 1.66) = 34mg/dl 1.49 (0.92, 2.43) BMI 1.64 (1.04, 2.58) = 9.7kg/m2 3.93 (2.19, 7.05) SBP 2.80 (1.85, 4.24) = 49mmHg 1.69 (1.16, 2.47) SMOKE 1.70 (1.17, 2.47) (cig/day) = 30 cig/day 1.89 (1.16, 3.07) AGE 2.05 (1.27, 3.33) 45-54 AGE 3.21 (1.95, 5.29) 2.85 (1.72, 4.74) 55-64 AGE 4.30 (2.06, 8.98) 3.73 (1.67, 8.35) 65-69

  27. General framework for estimation and inference in failure time regression models • Main study/validation study studies The data: (Di, Ti, Xi, Vi), i = 1, . . ., n1 main study subjects (Di, Ti, xi, Xi, Vi), i = n1 + 1, . . ., n1 + n2 validation study subjects where Ti = survival time Di = 1 if case at Ti, 0 o.w. xi = perfect exposure measurement Xi = surrogate exposure measurement for x Vi = other perfectly measured covariate data - assume sampling into validation study is at random Spiegelman and Logan, submitted

  28. Effect of radon exposure on lung cancer mortality rates: UNM uranium miners Mortality RR(95% CI) = 100 WLM 500 WLM Uncorrected 3.52 (0.658) 1.4 (1.3, 1.6) 5.8 (3.1, 11) EPL 5.00 (1.00) 1.7 (1.4, 2.0) 12 (4.6, 32) • > 30% attenuation in • policy implications for risk assessment

  29. Nutritional epidemiology: Tworoger SS, Eliassen AH, Rosner B, Sluss P, Hankinson SE. Plasma prolaction concentrations and risk of premenopausal breast cancer. Cancer Research, 2004;64:6814-6819. Hankinson SE, Willett WC, Michaud DS, Manson JE, Colditz GA, Longcope C, Rosner B, Speizer FE. Plasma prolaction levels and subsequent risk of breast cancer in postmenopausal women. Journal of the National Cancer Institute 1999; 91:629-634. Smith-Warner SA, Spiegelman D, Adami H, Beeson L, van den Brandt P, Folsom A, Fraser G, Freudenheim J, Goldbohm R, Graham S, Kushi L, Miller A, Rohan T, Speizer FE, Toniolo P, Willett WC, Wolk A, Zeleniuch-Jacquotte A, Hunter DJ. Types of dietary fat and breast cancer: a pooled analysis of cohort studies. International Journal of Cancer 2001; 92:767-774. Holmes MD, Stampfer MJ, Wolf AM, Jones CP, Spiegelman D, Manson JE, Coldditz GA. Can behavioral risk factors explain the difference in body mass index between African-American and European-American women? Ethnicity and Disease 1999; 8:331-339. Rich-Edwards JW, Hu F, Michels K, Stampfer MJ, Manson JE, Rosner B, Willett WC. Breastfeeding in infancy and risk of cardiovascular disease in adult women. Epidemiology, 2004; 15:550-556. Koh-Banerjee P, Chu NF, Spiegelman D, Rosner B, Colditz GA, Willett WC, Rimm EB. Prospective study of the association of changes in dietary intake, physical activity, alcohol consumption, and smoking with 9-year gain in wais circumference among 15,587 men. Am J Clin Nutr 2003; 78:719-727. Koh-Banerjee P, Franz M, Sampson L, Liu S, Jacobs Jr. DR, Spiegelman D, Willett WC, Rimm EB. Changes in whole grain, bran and cereal fiber consumption in relation to 8-year weight gain among men. Am J Clin Nutr, 2004; 5:1237-1245.

  30. Environmental epidemiology Keshaviah AP, Weller EA, Spiegelman D. Occupational exposure to methyl tertiary-butyl ether in relation to key health symptom prevalence: the effect of measurement error correction. Environmetrics, 2002; 14:573-582. Thurston SW, Williams P, Hauser R, Hu H, Hernandez-Avila M, Spiegelman D. A comparison of regression calibration methods for measurement error in main study/internal validation study designs. Journal of Statistical Planning and Inference, 2005; 131:175-190. Fetal lead exposure in relation to birth weight; MS/IVS; bone lead vs. cord lead (r=0.19) Weller EA, Milton DK, Eisen EA, Spiegelman D. Regression calibration for logistic regression with multiple surrogates for one exposure. Journal of Statistical Planning and Inference, 2007; 137:449-461 . Metal working fluids exposure in relation to lung function; MS/EVS; job characteristics vs. personal monitors (r=0.82) Horick N, Milton DK, Gold D, Weller E, Spiegelman D. Household dust endotoxin exposure and respiratory effects in infants: correction for measurement error bias. Environmental Health Perspectives, 2006; 114:135-140. Li R, Weller EA, Dockery DW, Neas LM, Spiegelman D. Association of indoor nitrogen dioxide with respiratory symptoms in children: the effect of measurement error correction with multiple surrogates. Journal of Exposure Analysis and Environmental Epidemiology, 2006; 16:342-350.

  31. SOFTWARE IS AVAILABLE! • http:/www.hsph.harvard.edu/facres/spglmn.html SAS macros for regression calibration (Rosner et al., AJE, 1990, 1992; Spiegelman et al., AJCN, 1997; Spiegelman et al, SIM, 2001) in main study/validation study designs • STATA (Carroll et al. SIMEX, regression calibration) So why are methods under-utilized? No validation data Insufficient training of statisticians & epidemiologists Either/or about assumptions

  32. Quantitative correction for selection bias: DesignAnalysis main study/’selection’ study ML SPE E-E Note: large overlap w/ missing data literature when D is missing, potential for selection bias References: Little & Rubin, Wiley, 1986 Scharfstein et al., 1998 Rotnitzky et al., 1997 Robins et al., 1995 ML SPE E-E

  33. Basic idea: Let I=1 if selected, 0 otherwise, Pr (I | E, C) = selection probability Selection study has data on those not in main study (Di, Ei, Ci = (Ci, Ui ), i=1, …, n2) Surrogates for D, risk factors for D Mail, phone, house visit to get data IPW: Pr -1(Ii = 1 | Di, Ei, Ci)= Wi Use PROC GENMOD w/ robust variance + weights Wi; i=1, …, n1 REPEATED SUBJECT = ID / TYPE = IND; For dependent censoring, (a.k.a. biased loss to follow-up) Assumes

  34. ENAR 2007 Spring Meeting Double Sampling Designs for Addressing Loss to Follow-up In Estimating Mortality Ming-Wen An, Johns Hopkins University Constantine Frangakis, Johns Hopkins University Donald B. Rubin, Harvard University Constantin T. Yiannoutsos, Indiana University School of Medicine Loss to follow-up is an important challenge that arises when estimating mortality, and is particular concern in developing countries. In the absence of more active follow-up systems, resulting mortality estimates may be biased. One design approach to address this is ‘double sampling’, where a subset of patients who are lost to follow-up is chosen to be actively followed, often subject to resource constraints, with the goal of obtaining valid and efficient estimators. We demonstrate our results using data from Africa, which were collected to estimate HIV mortality as part of the evaluation of the President’s Emergency Plan for AIDS Relief (PEPFAR).

  35. CONCLUSIONS - Methods EXIST for efficient study design and valid data analysis when standard design with standard analysis gives the wrong answer - Why do epidemiologists routinely adjust for one source of bias only? (confounding by measured risk factors) - Barriers to utilization • software gaps • software unfriendly, no QC • inadequate training of students + practitioners (Epi & Biostat) • are two-stage designs fundable @ NIH?

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