Condition No.Condition NameWeight
1Acute myocardial infarction5
2Cerebral vascular accident11
3Congestive heart failure13
4Connective tissue disorder4
5Dementia14
6Diabetes3
7Liver disease8
8Peptic ulcer9
9Peripheral vascular disease6
10Pulmonary disease4
11Cancer8
12Diabetes complications-1
13Paraplegia1
14Renal disease10
15Metastatic cancer14
16Severe liver disease18
17HIV2
Spell-based. The following rules were applied to all of the OPER codes in a spell in the order of preference: 
SituationCHOSEN_OP
Spell has none the OPER codes listed belowFirst OPER code that isn’t “&”
AAA code in spellFirst AAA
Both PTCA and Contrast codes somewhere in spell, but no CABG codeFirst PTCA
Both CABG plus PTCA in spellIf the OPDAT for the PTCA is the same or one day after the OPDAT for the CABG, pick the PTCA, otherwise pick the CABG. (If OPDATs are missing, pick the CABG.)
Both CABG plus Carotid in spellFirst CABG
Otherwise…Pick the first op which has a code in the table below.
  
OPER codes fall into the above groups based on the following (the codes must begin with one of the appropriate values): 
TypeDefinition
CABGK40, K41, K42, K43, K44, K45, K46
PTCAK49, K50
ContrastK63, K65
CarotidL29
AAAL183, L193, L203, L213, L184, L185, L186, L194, L195, L196, L204, L205, L206, L214, L215, L216
ListedA01, A02, A08, A12, A38, A40, A41, A52, A65, A83, A84, B27, B28, C12, C31, C32, C33, C34, C35, C60, C71, C72, C73, C74, C75, C77, C82, D03, D15, E03, E04, E25, E29, E36, E49, E51, E53, E54, F09, F10, F22, F34, G01, G02, G03, G14, G15, G16, G17, G18, G19, G27, G28, G35, G43, G44, G45, G52, G53, G58, G69, G70, G71, G78, H01, H02, H04, H05, H06, H07, H08, H09, H10, H11, H13, H15, H20, H21, H22, H23, H24, H25, H26, H27, H28, H33, H44, H48, H50, H51, H52, H54, H56, J01, J02, J13, J14, J18, J38, J39, J40, J41, J43, J56, J69, K01, K02, K04, K05, K06, K07, K09, K10, K11, K12, K14, K18, K19, K20, K25, K26, K27, K28, K29, K30, K31, K34, K37, K40, K41, K42, K43, K44, K45, K46, K49, K50, K53, K60, K63, K65, K66, L01, L05, L06, L09, L10, L12, L18, L19, L20, L21, L29, L33, L35, L48, L49, L50, L51, L52, L53, L56, L57, L58, L59, L60, L62, L63, L85, L87, L95, M01, M02, M14, M26, M27, M28, M29, M34, M42, M45, M65, N08, N09, N17, N30, P23, P31, Q01, Q02, Q03, Q07, Q08, Q10, Q11, Q14, Q17, Q18, Q35, Q36, Q38, Q39, Q41, Q49, Q50, R17, R18, R19, R20, R21, R22, R23, R24, R25, S05, S06, T19, T20, T21, T24, T42, T43, T46, T52, T54, T59, T60, T67, V09, V22, V25, V26, V29, V33, V34, V38, V39, V43, V47, V48, V49, W15, W19, W20, W21, W22, W23, W24, W25, W26, W28, W34, W37, W38, W39, W40, W41, W42, W46, W47, W48, W59, W79, W82, W83, W84, W85, W86, W87, W88, W90, X09, X29, X33, X35, X41
  
The “first” OPER code is decided on an EPISODE then the number of the OPER variable - for instance, OPER2 is considered “before” OPER5 in the same episode. They are not ordered by date.
OPDATn is a HES field and reflects the date associated with OPERn.