PENAPISAN TEKNOLOGI DIAGNOSTIK

Bambang Udji Djoko Rianto

The technology assesment iterative loop

Efficiency

Burden of illness

Efficacy

Screening & diagnosis

Community Effectiveness

Synthesis & implementation

Monitoring &reassessment

TUJUAN

Memahami berbagai masalah terkait dg penggunaan teknologi diagnostik bidang kedokteran/kesehatan

Melakukan penilaian kritis thd penggunaan suatu teknologi diagnostik

PENDAHULUAN

Ketepatan diagnosis: kunci sukses penanganan pasien

Pengembangan teknologi diagnostik membawa manfaat dan dampak

Disease/non diseaseDisease/non disease

TEKNOLOGI DIAGNOSTIKTEKNOLOGI DIAGNOSTIK

AccurateAccurate SafeSafe Therapeutic impactTherapeutic impact

Pendahuluan

Jumlah & rerata CT-scanner/1 juta penduduk

Jumlah CT Scanner

CT scanner/juta penduduk

Negara

1986 1988 1986 1988 AS Jepang Perancis Belgia Jerman Barat Denmark Belanda Inggris Itali

3000 3300 264 64

423 23 45

149 210

4991 5448 350 118 595

? 83

204 338

12.8 27.5 4.7 6.4 6.9 4.6 3.2 2.7 3.5

21.7 44.3 6.3

12.1 9.8 ?

5.7 3.6 5.9

Jumlah & rerata MRI/ 1 juta penduduk

Jumlah MRI Rerata MRI/juta penduduk

Negara

1986 1988 1986 1988

AS Jepang Perancis Belgia Jerman Barat Belanda Inggris Itali

110 10 29 7 41 2 14 13

1150 256 34 7

91 7

28 29

0.5 0.1 0.5 0.7 0.7 0.4 0.3 0.2

5.0 2.0 0.6 0.7 1.5 0.5 0.5 0.5

Test-treatment thresholds

Prevalence (pre-test probability) of target disoreder

0 .10 .20 .30 .40 .50 .60 .70 .80 .90

Do not test

Do not treat

Test, & treat on the basis of the

test’s results

Do not test

Get on with treatment

A B

Penilaian teknologi diagnostik

Tingkat akurasi Tingkat ketelitian Peruntukan teknologi diagnostik Evaluasi teknis Peranan dalam proses pengambilan keputusan

terapetik Peranan dalam penurunan morbiditas dan

mortalitas Keuntungan bagi klinisi Keuntungan bagi pasien

Diagnostic accuracy Sensitivitas Spesifisitas Likelihood ratio

+ -

+

Penyakit

Test

Truepositive

Falsepositive

Falsenegative

Truenegative

-

DEFINISI

Sensitivity: proporsi hasil test positif pada kelompok penderita

Specificity: proporsi hasil test negatif pada kelompok orang tanpa penyakit

Positive PV: probabilitas penyakit pada penderita dengan hasil test positif

Negative PV: probabilitas seseorang dengan hasil test negatif untuk benar-benar bebas dari penyakit

Sensitivity = a / (a+c)Specificity = d / (b+d)Accuracy = (a+d) / N

+ PV = a / (a+b)- PV = d/ (c+d)Prevalence = (a+c) / N

+ -

+

Gold Standard

Hasiltest

a b

c d-

a+b

c+d

a+c b+d N

2 Pendekatan ttg penampilan diagnosis

Prevalensi Sensitivitas/Spesifisitas

Nilai ramal

Pre-testprobability

Rasiokemungkinan

Post-testprobability

Likelihood Ratio Likelihood ratio positif: rasio hasil tes

positip yang dijumpai pada kelompok sakit dan kelompok tidak sakit

Likelihood ratio negatif: rasio hasil tes negatip yang dijumpai pada kelompok sakit dan kelompok tidak sakit

a/a+cLR (+) = --------

b/b+d

c/a+cLR (-) = --------

d/b+d

+ -

+

Gold Standard

Hasiltest

a b

c d-

a+b

c+d

a+c b+d N

Lieklihood ratio

>10 atau < 0,1, menghasilkan perubahan yg besar dari pre dan post test probability. Dan sering conclusive

5-10 dan 0,1-0,2, perubahan sedang 2-5 daan 0,2-0,5 perubahan kecil (kadang-

kadang penting) 1-2 dan 0,5-1, mengubah probability kecil

sekali (dan jarang penting)

Ketelitian diagnosis

Skala nominal: un-weighted kappa Skala ordinal: weighted kappa Skala interval/rasio: intra-class coefficient

correlation (ICC), CV

Peruntukan teknologi diagnostik Menegakkan diagnosis Menyingkirkan diagnosis Skrining

Technical evaluation

Prosedur sederhana Risiko minimal Interpretasi jelas (risiko false positive rendah) Risiko kesalahan pembacaan akibat kesalahan

prosedur operasional kecil Ketergantungan terhadap rekonfirmasi diagnosis

atau second opinion kecil

Diagnostic impact

Mendeteksi penyakit pada fase dini Rekonfirmasi terhadap prosedur diagnostik

sebelumnya Hasil mempengaruhi prognosis Mengurangi risiko keraguan

Therapeutic impact

Mensupport therapeutic decision making process

Early treatment Mengubah kebijakan terapi yang sudah

diputuskan

Health impact

Early warning system Morbiditas & mortalitas turun Quality of health care Reassurance

Seberapa besar kontribusinya terhadap therapeutic decision making process

Prompt action

Keuntungan yang diperoleh melebihi cost yang dikeluarkan

Membantu menetapkan terapi yang lebih do

more good than harm

Prompt treatmentPrompt treatment

Early diagnosisEarly diagnosis

morbiditasmortalitasmorbiditasmortalitas

Seberapa besar kontribusinya terhadap penurunan mortalitas dan morbiditas

Apa keuntungannya bagi klinisi

Menghilangkan keraguan diagnosis Improving confidence Lebih terfokus pada pilihan terapi Mengurangi risiko malpractice Improving quality of care

Morbidity/mortalityMorbidity/mortality

Quality of lifeQuality of life

DisabilityDisability

Opportunity costOpportunity cost

Patient satisfactionPatient satisfaction

Apa keuntungannya bagi pasien

Should general practitioner perform diagnostic tests on patients before prescribing antibiotics?,BMJ 318, 799-802 Kendali resistensi thd antibiotik tergantung

perilaku peresepan yg rassional oleh dokter umum.

Pemeriksaan mikrobiologis merupakan dasar pemberian antibiotik yg rasional. Tetapi hal ini memiliki kendala

Salah satu cara untuk mengatasi masalah ini di Denmark melakukan pemeriksaan mikrobiologis menggunakan mikroskop fase kontras dan kit diagnostik sederhana (near patient testing)

Keuntungan near patient testing Hasil pemeriksaan lebih cepat tersedia

dan keputusan dapat segeraa diambil Birokrasi dikurangi. Menghemat waktu,

mengurangi problem komunikasi, menghemat uang, lebih murah dan mendapat tambahan pendapatan.

Isu tentang mutu

Baku pemeriksaan ditempat praktek harus seimbang dg yg di laboratorium

Syarat pemeriksaan: sederhana, cepat, handal, mudah dibaca dan diinterpretasikan

Contoh: pemeriksaan mikroskopis fase kontras untuk ISK, vaginitis/vaginosis, pharyngotonsilitis, dermatophytosis, perianal pruritus, mononukleosis

Kepentingan near patient tests

Paling penting dilakukan untuk discharge vagina, dysuria, pharyngitis.

Pemeriksaan mikroskopis fase kontras di tempat praktek umum lebih teliti dibanding di laboratorium

Berfungsi sbg skrining pemeriksaan berikutnya, misalnya biakan, pemeriksaan Chlamydia, athropic vaginitis

Aspek uji diagnosis dalam praktek dokter umum Apakah uji/pemeriksaan layak dan valid?

Perlu selektif, pelatihan dan kendali mutu. Grup A streptococcus vs ASTO. Test strip vs metode skoring klinis.

Apakah uji/pemeriksaan mempercepat kesembuhan? Penurunan keluhan vs kekambuhan; 50% bakteriuria akan sembuh dlm waktu 3 hari tanpa antibiotik

Aspek-aspek uji diagnosis dalam praktek dokter umum

Apakah uji/pemeriksaan mencegah komplikasi?

Apakah pasien diuntungkan? Apakah uji/pemeriksaan cost-effective?

Kesimpulan

Pemeriksaan diagnosis untuk infeksi akut dilakukan jika ada bukti yg kuat ttg validitas, kelayakan, dan cost-effectivenes

Sebelum ada bukti yg kuat dokter umum dianjurkaan untuk memberikan obat simtomatis untuk infeksi yg paling sering dijumpai tanpa tergantung pd pemeriksaan diagnosis maupun antibiotik

The impact of medical imaging on physician’s diagnostic and therapeutic thinking Eur. Radiol. 8: 488-90

Pendahuluan

Ada perubahan kecenderungan bahwa pemeriksaan radiologi “requested” dari pada “ordered”

Permintaan pemeriksaan sering didiskusikan dalam pertemuan antara dokter klinis dan radiolog dengan memperhatikan kondisi klinis pasien, penampilan diagnosis dari bbrp pilihan, biaya, ketersediaan, daan expertise.

5 tahap dalam penilaian teknologi radiologi

1. Technical performance

2. Diagnostic performance

3. Diagnostic impact – keputusan diagnostik

4. Diagnostic impact – keputusan terapi

5. Impact on health

Diagnostic thinking

Dulu diagnosis pd pasien rawat jalan dpt ditegakkan dg anamnesis yg baik dan pemeriksaan fisik

Modern radiologi mungkin dpt mengubah fenomena ini

Radiolog dpt bekerja sama dg klinisi dlm penatalaksanaan pasien

Diagnostic thinking

Diagnosis klinis: peran radiologi kurang tampak apabila klinisi memberikan diagnosis klinis terlalu luas, begitu juga sebaliknya

Diagnostic confidence, ditetapkaan dg bbrp cara: pre-test probability, hasil V/Q scan, 10 point scale, VAS, LR, diagnostic entropy

Diagnostic thinking

Displacement of other investigations: pemeriksaan alat lama dan alat baru, alat baru dpt menggantikan alat lama, misalnya MRI pada meatus auditorius interna menggantikan pemeriksaan neurofisiologis

Health economists and statisticians

Therapeutic thinking

Pilihan terapi tersedia setelah diagnosis ditegakkan. Pilihan ini juga tergantung dari kwalifikasi pengirim

Pengembangan algoritme

How Often Should We Screen for Cervical Cancer? AU: Sarah Feldman, M.D., M.P.H. SO: New Eng J of Med, Volume 349, Number 16; October 16,

2003 Over the past 60 years, the mortality from cervical

cancer has decreased dramatically. Much of the reduction has been due to the widespread use of the Papanicolaou test, which has enabled clinicians to detect cervical intraepithelial neoplasia before it progresses to cervical cancer and to detect cervical cancer at an early stage.

When cervical cancer is detected early, the five-year survival rate is more than 90 %

PAP Smear test

> 80 % of women undergoing screening in any two-year period and > 90 % having been screened at least once.

Questions remain about optimal screening strategies. One key question is the optimal frequency of testing.

Cost–benefit analyses have suggested that lifelong annual screening may not result in substantially better outcomes than less frequent screening and is much more costly. With this in mind, the American Cancer Society recently revised its guidelines for screening

PAP Smear test

Recommending intervals between screenings ranging from one to three years, depending on several factors, such as age, screening history, type of Papanicolaou smear, and history of immunosuppression.

Other guidelines have also suggested screening less frequently than annually after three consecutive normal annual Papanicolaou tests and pelvic examinations. Yet there are not many data to support these recommendations.

Risk of Cervical Cancer Associated with Extending the Interval between Cervical-Cancer Screenings

AU: Sawaya et al

SO: New Eng J of Medicine, Volume 349, Number 16; October 16, 2003

Methods

We determined the prevalence of biopsy-proven cervical neoplasia among 938,576 women younger than 65 years of age, stratified according to the number of previous consecutive negative Papanicolaou tests. Using a Markov model that estimates the rate at which dysplasia will progress to cancer, we estimated the risk of cancer within three years after one or more negative Papanicolaou tests, as well as the number of additional

Papanicolaou tests and colposcopic examinations that would be required to avert one case of cancer given a particular interval between screenings.

Result

Among 31,728 women 30 to 64 years of age who had had three or more consecutive negative tests

The prevalence of biopsy-proven cervical intraepithelial neoplasia of grade 2 was 0.028 %

The prevalence of grade 3 neoplasia was 0.019 % None of the women had invasive cervical cancer

Result

According to our model, the estimated risk of cancer

with annual Papanicolaou tests for three years :

2 in 100,000 among women 30 to 44 years of age,

1 in 100,000 among women 45 to 59 years of age,

1 in 100,000 among women 60 to 64 years of age;

these risks would be 5 in 100,000, 2 in 100,000, and 1

in 100,000, respectively, if screening were performed

once three years after the last negative test.

Result

To avert one additional case of cancer by screening 100,000 women annually for three years rather than once three years after the last negative test, an average of 69,665 additional Papanicolaou tests and 3861 colposcopic examinations would be needed in women 30 to 44 years of age and an average of 209,324 additional Papanicolaou tests and 11,502 colposcopic examinations in women 45 to 59 years of age.

Conclusion

As compared with annual screening for three years, screening performed once three years after the last negative test in women 30 to 64 years of age who have had three or more consecutive negative Papanicolaou tests is associated with an average excess risk of cervical cancer of approximately 3 in 100,000.

Colorectal cancer screening: an overview of available and current recommendations

Early DS, Southern Medical Journal, 92 (3):258-265

Colorectal cancer screening

Skrining pd asimtomatik dpt menurunkan insidensi dan kematian

Database medline: artikel yg memuat rasional skrining kanker colorectal, metode yg digunakan, hasil guna dan rekomendasi yg digunakan saat ini

Hasil: metode: flexible sigmoidoscopy, fecal blood test, barium enema, colonoscopy. Metode yg digunakan dan frekwensi skrining tergantung dr risiko

Colorectal cancer screening

Penerimaan skrining oleh pasien dan dokter belum optimal

Masih diperdebatkan: Potensi skrining untuk mencegah

kematian dari ca colorectal, Cost effectiveness jika digunakan

untuk populasi umum.

Terima Kasih