This afternoon when i walked through the flyover. I met a black cat. It's so rare for me to see it. So i stopped and turned around. The cat also stopped. We just stared each other. I became fascinated. Since there's no people at that time i talked to the cat and say good bye. Then i turned my back pretending to walk away. The cat also continued its walking. When the cat walked away I stopped and took a look at it. I saw the cat took a little jump when it walked down the stairs. That is so cute. Well it’s just a small thing actually. But we can get something from that. I mean, even an animal like a cat knows what’s the function of a flyover but we, as a human, many of us still prefer crossing through the street instead of using the flyover. The reason is because people love “instant” thing and sedentary life. Well we need to change that. I mean walking or jogging is the cheapest exercises, right. So why don’t we try that :)
Sunday, May 25, 2014
The Cat And Me
This afternoon when i walked through the flyover. I met a black cat. It's so rare for me to see it. So i stopped and turned around. The cat also stopped. We just stared each other. I became fascinated. Since there's no people at that time i talked to the cat and say good bye. Then i turned my back pretending to walk away. The cat also continued its walking. When the cat walked away I stopped and took a look at it. I saw the cat took a little jump when it walked down the stairs. That is so cute. Well it’s just a small thing actually. But we can get something from that. I mean, even an animal like a cat knows what’s the function of a flyover but we, as a human, many of us still prefer crossing through the street instead of using the flyover. The reason is because people love “instant” thing and sedentary life. Well we need to change that. I mean walking or jogging is the cheapest exercises, right. So why don’t we try that :)
Saturday, May 24, 2014
Soal IKM dan EBM Part 2
CASE-CONTROL
Data dari studi case control terhadap
miokardial infark (MI) telah diringkas sebagai berikut:
Usia
|
MI (-)
|
MI (+)
|
||
Bukan Perokok
|
Perokok
|
Bukan perokok
|
Perokok
|
|
<50
|
130
|
126
|
11
|
13
|
≥50
|
55
|
42
|
4
|
19
|
1. Estimasi Odd Ratio dari MI termasuk merokok (tanpa memperhatikan
usia)?
2. Estimasi Adjusted Odds Ratio. Apakah terdapat
beberapa efek confounding dari usia? Mengapa atau mengapa tidak?
3. Apakah usia merupakan efek modifier pada studi ini? Mengapa atau
mengapa tidak?
1. Menentukan OR dari MI (tanpa memperhatikan usia)
MI (+)
|
MI (-)
|
|
Perokok
|
32 (a)
|
168 (b)
|
Bukan Perokok
|
15 (c)
|
185 (d)
|
OR = ad/bc = 32(185)/168(15) =
5920/2520 = 2,349
Interpretasi:
Perokok memiliki
peluang 2,349 kali lebih besar terkena miokardial infark dibanding bukan perokok.
2. Menentukan
Adjusted OR
Usia <50
MI (+)
|
MI (-)
|
Total
|
|
Perokok
|
13 (a)
|
126 (b)
|
139 (a+b)
|
Bukan Perokok
|
11 (c)
|
130 (d)
|
141 (c+d)
|
Total
|
24 (a+c)
|
256 (b+d)
|
280 (n)
|
OR (<50) = ad/bc =
13(130)/126(11) = 1690/1386 = 1,219
Usia ≥50
MI (+)
|
MI (-)
|
Total
|
|
Perokok
|
19 (a)
|
42 (b)
|
61 (a+b)
|
Bukan Perokok
|
4 (c)
|
55 (d)
|
59 (c+d)
|
Total
|
23 (a+c)
|
97 (b+d)
|
120 (n)
|
OR (≥50) = ad/bc = 19(55)/42(4)
= 1045/168 = 6,22
Adjusted Odd Ratio
OR = (a1d1/n1
+a2d2/n2) : (b1c1/n1+b2c2/n2)
= (13(130)/280+19(55)/120)
: (126(11)/280+42(4)/120)
= (1690/280+1045/120)/(1386/280+168/120)
= (6,036+8,708)/(4,95+1,4)
=
14,744/6,35
=
2,322
Interpretasi:
Karena nilai crude OR ≠ Adjusted OR maka terdapat
confounding factor. Selisih crude OR dan adjusted OR yaitu 0,027 (2,349-2,322)
atau 27%. Selisih<10% maka confounding factor tidak penting/ potensial.
3. Menentukan usia sebagai efek modifier
Efek modifier adalah jika pengaruh pajanan terhadap
kejadian suatu penyakit dipengaruhi oleh level variabel lainnya.
Pada studi ini, nilai OR pasien usia <50 ≠ nilai OR
pasien usia ≥50 maka usia merupakan efek modifier yang mempengaruhi paparan
(merokok) terhadap kejadian MI.
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