The positive side of overdiagnosis

Does an immediate comprehensive panel of laboratory tests in

outpatient care improve patient outcomes?

Bram Vrijsen, Maarten ten Berg, Christiana Naaktgeboren,

Jolande Vis, Wouter van Solinge, Karin Kaasjager

Introduction

• Research on diagnostic error focuses on overutilization

• Underutilization is underappreciated

• Specific aspects of laboratory testing

– High volume

– Low costs per test

– Low burden on patients

– Few incidental findings

• More testing may lead to better outcomes and lower

costs

• Improved turn-around time of laboratory services

• Makes laboratory testing prior to consultation possible

• Evaluate different strategies, focusing on patient centered

outcomes

• Setting: internal medicine outpatient clinic

POORT study

(Patient Outcomes Of Rapid Testing)

Three strategies

Information at referral

Outcomes

• Primary outcome

– Time to diagnosis

• Secondary outcomes

– Appropriateness of laboratory testing

• Number of inappropriate tests ordered

• Number of appropriate tests not ordered

– Consequences of diagnostic error for patients

– Health care utilization and costs

– Patients’ preference

Pilot of the POORT study

To evaluate logistics of lab testing prior to consultation

Based on the first 100 included participants

Comparison of 2 laboratory test strategies:

- Individualized laboratory panel based of the information

at referral (questionnaire)

- Standard test panel

Appropriateness of tests ordered

• From the original blood sample, additional tests are

performed after three months, so that every patient has

the same set of tests performed

• Expert panel evaluates which tests were inappropriately

ordered or not ordered

Standard panel prior to consultation

BLOOD URINEHaemoglobin Urine screening (dipstick)Cell counts / differentialSodiumPotassiumCalciumUreaCreatinineAlkaline phosphataseγ-GTGlucoseASATALATLDHAlbuminCRPTSHESR

Extended panel (after 3 months)

BLOOD URINEHaemoglobin Phosphate Urine screening (dipstick)Cell counts / differential Magnesium SodiumSodium Bicarbonate PotassiumPotassium Osmolality ChlorideCalcium Free-T4 CalciumUrea Thyroid antibodies PhosphateCreatinine Ferritin MagnesiumAlkaline phosphatase Vitamin B12 Osmolalityγ-GT Folic acid Total proteinGlucose Homocysteine AlbuminASAT Methylmalonic acidALAT Free sol. transferrin rec.LDH Intrinsic factor antibodiesAlbumin Parietal cell antibodiesCRP HaptoglobinTSH Dir. Coombs / ZPPESR Hemoglobin electrophoresis

Flow chart

Patient characteristics

Sex Concurrent medical problemsFemale 64 Yes 21Male 36 No 40

Unknown 39Age (mean + SD) 54 ± 17

Referral reason Concurrent medical problemsFatigue 25 Cardiovascular 13Abnormal laboratory test result 18 Pulmonary 6Gastrointestinal complaints 16 Diabetes 4Abnormal weight loss 10 Malignancy 4Lymphadenopathy / tumours 7 Rheumatological 8Other 20 Hematological 3Excluded 4 Gastro-intestinal 2

Thyroid 2Other 19

Time to diagnosis

Median: 42.5 d (11.3 – 92)

Comparison of lab on referral and broad

panel

All values are medians with IQR

Number of necessary tests

10 (5-12)

Laboratorypanel

Number of ordered tests

Inappropriatetests ordered

Necessary tests not ordered

Individualized 18 (14 - 20) 10 (7 - 13) 2 (0 - 3)

Standard 22 (22 - 22) 14 (12 - 17) 1 (0 -2)

Medians with IQR

Patients’ consequences of inappropriately

ordered tests

Patients (n=94)

ReferralStandard

panel

Out of reference 81 85

Anxiety 2 4

Additional visits 8 9

Additional lab orders 18 21

Additional imaging 1 2

Missed diagnosis 0 0

Wrong diagnosis 0 0

Wrong therapy 0 0

Delay in diagnosis 5 6

Patients’ consequences per test (top five)

Total AnxietyAdditional

visits

Additional

lab orders

Additional

imagingDelay

Screening

(urine)19 1 4 12 0 2

ESR 6 1 0 2 0 3

GGT 6 0 2 3 1 0

ASAT 6 0 2 3 1 0

Hemoglobin 6 0 1 4 0 1

Patient preferences

Do you prefer to have as many appointments as possible

planned on one day?

Is it important for you to talk to your physician before

having laboratory tests performed?

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Not at all Slightly For the mostpart

Yes, totally

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Not at all Slightly For the mostpart

Yes, totally

Patient preferences

Do you object to more laboratory tests being performed

than are strictly necessary?

Do you mind if a second blood sample is drawn on the

same day, because additional tests need to be performed?

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Not at all Slightly For the mostpart

Yes, totally

0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Not at all Slightly For the mostpart

Yes, totally

Conclusion and discussion

• The negative side-effects of overtesting appear to be limited.

• Patients prefer to have clustered appointments on one day.

Most patients do not mind a second blood collection on the

same day.

• Research on over- and underutilization of laboratory testing

should focus on patient centered outcomes.

• We hypothesize that performing a protocolized laboratory

panel prior to the consultation leads to a shorter time to

diagnosis.