Innovative EBP: Teaching NNT Through the Use of

Practice, Role Play, and Story

-Darcy Vavrek ND MS

University of Western States

Portland, OR

Today’s main points:

• Lecture introduces story (7 slides)

– Clinical application motivates learning– Color card voting lets students see that EBP fosters

intelligent discussion but not agreement

• Practice problems (1 slide, 1 handout)

– With time management strategy

• Role play (4 slides, uses practice problems)

– Open ended exercise breaks up lecture– Group discussion at the end motivates learning

Randomized Controlled Trials

• Experimental & Control Event Rates

• Risk Difference (RD)

• Numbers needed to Treat (NNT)

Surgery vs Prolonged Conservative Treatment for Sciatica

• Randomized Clinical Trial• Severe sciatica of 6 to 12 weeks duration• U.S. – multi-center• 283 participants

– Early surgery – 125/141 had microdiskectomy– Conservative treatment – 55/142 underwent surgery

• Outcomes:– Roland disability questionnaire, VAS for leg pain,

patient report of perceived recovery

Control & Experimental Event Rates

Event

Yes No

Treatment a b

Control c d

• Experimental event ratea/(a+b) = rate of event in treatment group

• Control event ratec/(c+d) = rate of event in control group

Unadjusted Conservative Care & Early Surgery Event Rates at 2 weeks

Patient Reported Recovery

Yes No

Early Surgery 87 54

Conservative Care 45 97

• Early surgery event rate87/(87+54) = 87/141 = 61.70%

• Conservative care event rate45/(45+97) = 45/142 = 31.69%

Early Surgery (n=141)

• Early surgery, microdiskectomy, scheduled within 2 weeks after assignment and cancelled only if spontaneous recovery occurred before surgery.

• Rehabilitation of patients at home was supervised by physiotherapists using a standardized exercise protocol.

• 16 recovered before surgery could be performed.• Median time to surgery for the 125 remaining was

1.9 weeks.

Conservative Care (n=142)

• General practitioners informed patients about favorable prognosis, natural course of illness, and expectation of successful recovery.

• Treatment aimed at restoring ADLs.• Prescription pain meds as needed.• Patients fearful of moving were referred to physiotherapist.• Surgery was recommended if:

– Sciatica present 6 months after randomization– Increasing leg pain not responsive to medication– Progressive neurological deficits

• Median time to surgery, for 55 who had surgery, was 14.6 weeks.

Early Surgery vs Conservative Care

• Those with recommended early surgery had a higher rate of recovery, at 2 weeks, compared to those receiving conservative treatment.

– Early surgery – 87/141 achieved “complete” or “nearly complete” disappearance of symptoms, at 2 weeks, as measured on a 7-point Likert scale.

• Early surgery event rate: 87/141 recovered (61.7% unadj.)

– Conservative treatment – 45/142 achieved recovery at 2 weeks • Conservative care event rate: 45/142 recovered (31.7% unadj.)

• Peul WC, Houwelingen HC, van den Hout WB, Brand R, Eekhof JAH, Tans JTJ, Thomeer RTWM, Koes BW. Surgery versus prolonged conservative treatment for sciatica. N Engl J Med 2007;356:2245-56.

Risk Difference (RD)

• Used in RCTs• Is the difference in the probability of an event between

the treatment and control groups • Thus, the formula for calculating RD is similar to

calculating harm in previous lecture:

• For early surgery vs conservative care this is: – 62%-32%=30% improvement – In the outcome, patient perceived recovery

a-

c

a+b c+d

Number needed to treat (NNT)• NNT: The number of patients who would need to be treated in

order to achieve one additional good outcome

• Unadjusted calculation from lecture: – 1/0.30 = 3.3 NNT

• Adjusted calculation reported in paper: – 1/.36 = 2.8 NNT

• 2.8 patients need to be treated, on average – for one more patient to get appreciable benefit from recommendation

of early surgery compared to conservative care– when assessed by “complete” or “nearly complete” resolution of

symptoms

1=

1

(a/(a+b))-(c/(c+d))

Risk Difference

NNT handout practice problems

• Columns – 2, 8, 26, and 52 weeks

• Third row – Adjusted risk difference

• Fourth row – 95% CI for the adjusted RD

• Calculate– The adjusted NNT– 95% CIs

• In-class exercise– Participants will use these numbers in role play

Breakout groups – 4 per group

• Role play– Physician – Intern – Patient – Family member

Patient History: LBP c Sciatica• 55yo male presents for follow-up of LBP with

radiculopathy (sciatica).• Pain began 5 months ago after a work injury.• Unresponsive to treatment after 3 months. • No pain with sitting.• Imaging confirms a midline herniated disc.• Patient is anxious and depressed.• Surgery consult recommends surgery.

Operating Bias of Role Players

• Physician – does not want to talk patient into surgery

• Intern – wants to talk patient into surgery

• Patient – does not want surgery

• Family member – wants patient to get surgery

Reference article: Peul WC, Houwelingen HC, van den Hout WB, Brand R, Eekhof JAH, Tans JTJ, Thomeer RTWM, Koes BW. Surgery versus prolonged conservative treatment for sciatica. N Engl J Med 2007;356:2245-56.

Pros/Cons

• Cons discussed:

• Pros discussed:

• Decisions made:

Pros/Cons

• Cons discussed:– Cost of surgery – expensive

• How much does 12 months of treatment• Insurance factors – what covered• Self employed/ employer• Workers comp could take time to get approved

– Cusp of marked improvement– Patient does not want surgery– Surgery might not work– Surgery is scary/risky– Recurrence risk– Pain pathways may recur– Family member wants to kick out family member– Lack of mobility forever

• Pros discussed:– Cusp of market improvement– If insurance benefit– Return to work faster– Less whining – may lead to less anxiety depression– May have stronger placebo effect– Chores around house– Replacement discs

• Decisions made:– Conservative care for 4 more weeks, wait 1 to 3 more months– Having surgery (golf), another, surgery– No surgery– Palmer – one of the groups had the pt die– Updated MRI after some more waiting