Pubh 7 420 clinical trials
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PubH 7- 420 Clinical Trials. Instructor: Jim Neaton 612-626-9040 [email protected] 2221 University Ave SE, Room 200 Text:Fundamentals of Clinical Trials Friedman, Furberg , and DeMets Evaluation: Homework: 3 exercises (15%) Group discussion topics (5%) Protocol project (30%)

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PubH 7- 420 Clinical Trials

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Pubh 7 420 clinical trials

PubH 7- 420Clinical Trials

Instructor: Jim [email protected] University Ave SE, Room 200

Text:Fundamentals of Clinical TrialsFriedman, Furberg, and DeMets

Evaluation: Homework: 3 exercises (15%)Group discussion topics (5%)

Protocol project (30%)

Mid Term (20%)Final (30%)

Web Site: http://www.biostat.umn.edu/~ph7420


Tas for pubh 7420

TAs for PubH 7420

YunBai – [email protected]

Kristin Cunanan – [email protected]

Debashree Ray – [email protected]


Group work protocol and discussion topic groups

Group Work: Protocol and Discussion Topic Groups

  • Six groups, 10-11 multidisciplinary members.

  • Three protocol topics, 2 groups assigned to each protocol topic.

  • Twelve discussion topics, 2 per group:

    • 15 minute presentation on topic (max of 7 slides)

    • Each topic should be presented by 2 people; each person should only present one topic. All group members are expected to participate (see calendar for schedule).


Protocol project

Protocol Project

  • Protocol

    • 10 -12 pages.

    • On the last page of the protocol indicate the members of the team and the sections they contributed to.

    • Turn in by the last day of class.

  • Presentation

    • 20 minutes during the last 2 weeks of class, followed by questions and discussion.


Outline of protocol

Outline of Protocol

  • Background and rationale for study

  • Study design

    • Objectives (primary, secondary, subgroup hypotheses)

    • Primary and secondary endpoints (efficacy and safety)

    • Inclusion and exclusion criteria

    • Treatments

    • Sample size

  • Data collection plan and follow-up schedule

  • Data analysis plan, including plan for interim monitoring and guidelines for early termination


Advice for groups

Advice for Groups

  • Elect a chairperson and rapporteur

  • Divide up the work among all group members

  • Give each member a list of names and email addresses in group

  • Plan to meet 6-7 times during the semester

  • Plan to have 2 members present the discussion topic and 3 members present the protocol


General methods of investigation

General Methods of Investigation

1.Chance observations

2.Case histories

  • individual cases

  • case series

    3.Uncontrolled trials of an intervention

    4.Cross-sectional (naturalistic) studies

    5.Case-control studies

    6.Prospective follow-up studies

    7.Randomized clinical trial

No planned

concurrent

comparison

group


Did investigator assign exposures

Did Investigator Assign Exposures?

Yes

No

Observational study

Experimental study

Random allocation?

Comparison group?

Yes

No

Yes

No

Analyticalstudy

Descriptivestudy

Non-randomised controlledtrial

Randomised controlledtrial

Direction?

Exposure andoutcome atthe same time

ExposureOutcome

ExposureOutcome

Case-controlstudy

Cross-sectionalstudy

Cohortstudy

Grimes and Schulz, Lancet, 359:57-61, 2002.


Hierarchy of evidence

Hierarchy of Evidence

Coherence of evidence from multiple sources

Systematic review of well-designed, large randomized trials

Strong evidence from one large randomized trial

Systematic review of small trials (e.g., surrogate outcome studies)

Systematic review of from well-designed cohort studies

Strong evidence from one cohort study

Unsystematic observations (expert opinions)

Adapted from Devereaux PJ et al, Evidence-Based Cardiology, 2nd Edition, BMJ Books, 2003.


Rating schemes for clinical guidelines

Rating Schemes for Clinical Guidelines

  • Quality of Evidence (as per previous slide)

  • Strength of Recommendation+

    • A: Strong

    • B: Moderate

    • C: Optional

+ from DHHS guidelines for the treatment of HIV

http://www.aidsinfo.nih.gov/Guidelines


Types of clinical research in journals and press

Types of Clinical Research in Journals and Press

  • Fletcher and Fletcher (N Engl J Med 1979)

    • Review of articles published from 1946-1976

    • In 1976, 44% cross-sectional, 34% cohort studies, 5% randomized trials

    • “Predominant designs in 1976 were less accurate ways of conducting clinical research”.

  • Lai and Lane (PLoS One 2009)

    • Of 734 front-page stories 43% were presentations/abstracts

    • Of the journal articles reported, 3% were overviews of trials and 21% were randomized trials, 42% cohort studies and 31% expert opinions


Chance observations examples

Chance ObservationsExamples

  • Bleeding among children chewing gum containing aspirin to relieve the pain from tonsillectomies

    (Dr. Lawrence Craven) (see Dalen J, Arch Int Med 1991; 151:1066-1069)

  • Discovery of penicillin (Fleming) and digitalis (purple foxglove) (Withering)


Case histories or case report

Case Histories (or Case Report)

  • Most ancient and widely used method of clinical investigation

  • Most useful for disease with a specific etiologic agent

  • Standard for comparison is usually implicit

    The New England Journal of Medicine usually has a case described in each issue

    http://www.nejm.org/browse?category=clinicalcases


Case series

Case Series

  • Def. – aggregation of individual cases in one report; the series may include all persons with an outcome or all persons with an exposure and outcome, e.g., an epidemic or spontaneously reported adverse events

    Weaknesses

  • No concurrent control

  • Usually inadequate information about persons not developing the disease

  • Cases may not be representative; persons with disease are survivors of unknown population


Example case series

Example: Case Series

Jaffe et al. Acquired immune deficiency syndrome in the United States: The first 1,000 cases. J Inf Dis 148:339-45, 1983.

Purpose: To describe characteristics of the cases.


Case definition

Case Definition

Eligibility Criteria:

1.Biopsy proven Kaposi sarcoma (KS) or

2.Biopsy, histology, or culture proven infection moderately predictive of cellular immune deficiency

a.Protozoal and helminthic infections, e.g., Pneumocystis carinii pneumonia (now Pneumocystis jiroveci and recognized to be a fungal disease)

b.Fungal infections, e.g., esophageal candidiasis

c.Bacterial infections, e.g., atypical mycobacterial disease

d.Viral infections, e.g., cytomegalovirus disease

Exclusion Criteria:

1.Previous immunosuppressive therapy

2.Illness associated with immunosuppression

3.Persons with KS over 60 years of age

4.Persons under 10 years of age


Surveillance

Surveillance

1.Review of selected cancer tumor registries

2.Contact with selected physicians in 18 communities

3.Review of request for pentamidine isethionate by CDC Parasitic Diseases Drug Service

4.Reports from individual physicians and state health departments


Results

Results

  • 727 cases were homosexual or bisexual males; of remaining cases 155 were IV drug users

  • 75% of homosexual men were from New York or California

  • 48% of cases were 30 - 39 years of age

  • There was an excess of KS among homosexual / bisexual men

  • Distribution of cases by risk group changed over time


Case series summary

Case Series Summary

  • A descriptive study, i.e., not designed to address a specific hypothesis or estimate absolute risk of an outcome.

  • Key feature: Clear, reproducible case definition with a focus on person, place and time

  • Addresses 5 “W” questions: who, what, why, when, and where

  • Often the 1st approach taken and the results are used to generate specific hypotheses


Other examples of case series pandemic influenza a h1n1v

Other Examples of Case Series: Pandemic Influenza A (H1N1v)

  • Pneumonia and respiratory failure from swine-origin influenza A (H1N1) in Mexico (N Engl J Med 2009;361:680-689)

  • Critically ill patients with 2009 influenza A(H1N1) in Mexico (JAMA 2009; 302:1880-1887)

  • Hospitalized patients with 2009 H1N1 influenza in the United States, April-June 2009 (N Engl J Med 2009;361:1935-1944)

  • Emergence of a novel swine-origin influenza A (H1N1) virus in China (N Engl J Med 2009;360:2605-2615)


Case series helped define cohort studies as below with specific hypotheses

Case Series Helped Define Cohort Studies as Below with Specific Hypotheses

  • INSIGHT H1N1v Outpatient Study

    • Characterize patients with influenza-like illness, influenza A and H1N1v

    • Identify risk factors for hospitalization within 14 days of diagnosis

  • INSIGHT H1N1v Hospitalization Study

    • Characterize patients hospitalized with influenza A and H1N1v

    • Identify risk factors for death within 60 days of admission

  • For both studies:

    • Molecularly characterize the virus

    • Establish a repository of serum to study biomarkers.

Dwyer D et al. Vaccine 2011;295:B56-B62.


Example uncontrolled trial of an intervention

Example: Uncontrolled Trial of an Intervention

Moertel et al. A clinical trial of amygdalin (laetrile) in the treatment of human cancer. NEJM 306:201-6, 1982.

Purpose: To determine if laetrile was an effective and safe treatment for cancer.

Study preceded by retrospective analysis of laetrile users (estimated 70,000 people, 93 cases submitted, 67 with medical records, 6 “responders”). NEJM 299:549-552, 1978.


New laetrile study leaves cancer institute in the pits

“New Laetrile Study Leaves Cancer Institute in the Pits”

Science, October 1978


Did investigator assign exposures1

Did Investigator Assign Exposures?

Yes

No

Observational study

Experimental study

Random allocation?

Comparison group?

Yes

No

Yes

No

Analyticalstudy

Descriptivestudy

Non-randomised controlledtrial

Randomised controlledtrial

Direction?

Exposure andoutcome atthe same time

ExposureOutcome

ExposureOutcome

Case-controlstudy

Cross-sectionalstudy

Cohortstudy

Grimes and Schulz, Lancet, 359:57-61, 2002.


Pubh 7 420 clinical trials

Eligibility Criteria

1.Histologically proven cancer

2.No surgery, radiation or chemotherapy in past month

3.Good general condition (able to eat and get about alone)

4.No known cure

5.Measurable tumors

Treatment: Naturally derived laetrile

  • 21-day intravenous schedule followed by oral dose

  • High doses of vitamins

  • Restricted diet


Pubh 7 420 clinical trials

Response Variables (Endpoints):

  • Tumor size

    • Regression

    • Stable

    • Progression

  • Weight

  • Performance status

  • Side effects

  • Mortality


Results1

Results

179 patients entered; 178 followed

  • 1 partial responder

  • 54% with progression at end of IV schedule

  • All had progression after 7 months

  • Median survival: 4.8 months


Conclusion

Conclusion

“It must be concluded that amygdalin (Laetrile) in combination with high doses of vitamins, pancreatic enzymes, and a diet of the type employed by ‘metabolic therapists’ is of no substantive value in the treatment of cancer. Further investigation of clinical use of such therapy is not justified.”


Important features of this study

Important Features of This Study

  • Well-defined cases and treatment

  • Protocol for patient evaluation and analysis

  • Objective endpoints

  • Complete data with nearly all patients meeting evaluability criteria; and

  • The study was described in sufficient detail so that it could be replicated


Questions

Questions:

1.What is the comparison group?

2.Are the inferences to all cancer patients justified since the study was restricted to “uncurable” cases?

3.Is it ethical to conduct a randomized controlled clinical trial of laetrile?

  • Then?

  • Now?

    4.Are uncontrolled studies reasonable alternatives to randomized clinical trials when the endpoint is objective?


Laetrile study

Laetrile Study

Partial

Response

No

Response

Laetrile

1

174

175*

*One patient was ineligible and

3 could not be evaluated


Remarks by commentators

Remarks by Commentators:

“From a public health standpoint, it was unethical to conduct a clinical study that would supposedly test orthodox versus unorthodox treatments to resolve the laetrile controversy, but could not do so scientifically.”

“These conclusions are not justified … there was no control group with which the group of treated patients could be compared.”


Pubh 7 420 clinical trials

Special Situations When Uncontrolled Study May Be Appropriate

  • No other treatment to use as control

  • Untreated patients have very poor prognosis

  • Treatment not expected to have serious side effects

  • Potential benefit to patients large and unambiguous

  • Result of study likely to be widely accepted

  • Byar D, et al. NEJM, Vol 323, 1990.


Pubh 7 420 clinical trials

In the author’s response, they cited data from historical controls

  • Historical controls (def.) – a group of patients used for comparison that were diagnosed and treated for the disease of interest in the past.

  • Varying amounts of rigor are employed to define historical controls.


Disadvantages of historical controls

Disadvantages of Historical Controls

  • Comparability of controls and those given new treatment cannot be ensured.

  • May not be possible to reproduce inclusion/exclusion criteria or data when treatment follow-up begins (“time zero”).

  • Efficacy and safety outcomes may not be defined identically.

  • Concomitant treatments may vary (hopefully better now).

  • Outcomes may improve over time due to greater clinical experience.

  • Numbers of historical controls available may be small resulting in imprecise outcome rates.


Planned observational studies

Planned Observational Studies

1.Cross-Sectional – data collected at a single point in time (risk factors and disease endpoints measured simultaneously).

2.Case-Control - controls (non-cases) sampled from base population.

3.Prospective Follow-up (cohort) - controls (non-cases) not sampled; risk factor measurements made before endpoints occur.


Did investigator assign exposures2

Did Investigator Assign Exposures?

Yes

No

Observational study

Experimental study

Random allocation?

Comparison group?

Yes

No

Yes

No

Analyticalstudy

Descriptivestudy

Non-randomised controlledtrial

Randomised controlledtrial

Direction?

Exposure andoutcome atthe same time

ExposureOutcome

ExposureOutcome

Case-controlstudy

Cross-sectionalstudy

Cohortstudy

Grimes and Schulz, Lancet, 359:57-61, 2002.


Cross sectional study

Cross-Sectional Study

  • National Health and Nutrition Examination Survey (NHANES) – ongoing national survey conducted by the National Center for Health Statistics

    In 2007-2008 almost 17% of children and adolescents aged 2-19 years were obese

    http://www.cdc.gov/nchs/nhanes.htm


Pubh 7 420 clinical trials

Cross-Sectional StudyMRFIT: Association of left ventricular hypertrophy (LVH) by ECG and hypertensive status at baseline of trial

LVH

No LVH

Hypertensive

231

7,781

8,012

Normotensive

43

4,811

4,854

274

12,592

12,866

Prevalence of LVH among hypertensives =

231 / 8,012 = 2.9%

Prevalence of LVH among normotensives =

43 / 4,854 = 0.9%

Cross-sectional study + follow-up = cohort study.


Pubh 7 420 clinical trials

Cross-Sectional StudyAssociation of PCP and genderat baseline in trials and cohort studies carried out by the Community Programs for Clinical Research on AIDS (CPCRA)

PCP

No PCP

Men

371

1,189

2,260

Women

58

493

551

2,811

429

2,382

History of PCP among men = 371 / 2,260 = 16.4%

History of PCP among women = 58 / 551 = 10.5%

P-value = 0.001 for difference


Cd4 percent distribution for men and women

CD4+ Percent Distribution for Men and Women

CD4+

Men

Women

Total

< 50 22 13 20

50 - 99 11 6 10

100 - 149 8 7 8

150 - 199 7 8 8

≥ 200 52 66 54

Total100100100

Median213328232


Interrelationship between gender cd4 count and pcp

Gender

(risk factor)

PCP

(disease

endpoint)

CD4+

(confounder)

Interrelationship Between Gender, CD4+ Count, and PCP


Percent of patients with history of pcp according to cd4 count

Percent of Patients with History of PCP According to CD4+ Count

CD4+ (cells/mm3)

Percent with

PCP

Total

< 5056143.3

50 - 9927227.6

100 - 14922615.5

150 - 1992128.5

≥ 2001,5413.8


Confounding

Confounding

Confounder (def.)

  • A variable whose effect is entangled with the effect of other variables under study

  • A factor related to the disease endpoint being studied and to the risk factor being investigated


Modified question

Modified Question

To what extent do differences in the CD4+ distribution between men and women explain the difference (or lack of difference) in the prevalence of PCP between men and women?


Percent of patients with history of pcp by cd4 count and gender

Percent of Patients with Historyof PCP by CD4+ Count and Gender

Percent with PCP

< 5043.939.4

50 - 9928.918.2

100 - 14916.112.5

150 - 19910.70.0

≥ 2003.35.2

Total16.410.5

CD4+

Men

Women


Unadjusted and cd4 adjusted percent with history of pcp by gender

Unadjusted and CD4+ Adjusted Percent with History of PCP by Gender

Unadjusted16.410.50.001

CD4+ adjusted15.613.50.22

(direct method)

Men

Women

P-value


Common problems with inferences from cross sectional surveys

Common Problems with Inferences from Cross-Sectional Surveys

  • Chicken/egg dilemma (except for genetic factors)

  • By definition must consider prevalent cases rather than incident cases, thus data reflect determinants of death/recovery as well as etiology (Neyman bias or incidence-prevalence bias).

    Primary Utility: descriptive; hypothesis generation


Incidence and prevalence

Incidence and Prevalence

Incidence

Prevalence

Recovery/Death


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