Monday, May 12, 2025

Risk Estimates and Odds in Microsoft Excel, and Online calculator (Excel-based)

Risk Estimates and Odds B2 shows exposure and outcome, B2 shows exposure and outcome, B3 shows non-exposure and outc... B2 shows exposure and outcome,B3 shows non-exposure and outcome,C2 shows exposure and no outcome,C3 shows no exposure and no outcome Odds Ratio Odds Ratio Odds Ratio =(B2/B3)/(C2/C3) =(B2/B3)/(C2/C3) =(B2/B3)/(C2/C3) syntax syntax syntax The Odds Ratio is a measure of association between an exposure/treatment and an outcome. It tells us how much more likely (or less likely) the outcome is to occur in the exposed/treated group compared to the non-exposed/untreated group. The Odds Ratio is a measure of association between an exposur... The Odds Ratio is a measure of association between an exposure/treatment and an outcome. It tells us how much more likely (or less likely) the outcome is to occur in the exposed/treated group compared to the non-exposed/untreated group. illustration Patreon and LinkedIn links LinkedIn Profile /usmanzafarparacha /usmanzafarparacha /usmanzafarparacha LinkedIn Patreon profile /uzparacha /uzparacha /uzparacha Patreon Usman Zafar Paracha 1 Usman Zafar Paracha Usman Zafar Paracha example example example Suppose we have this data Suppose we have this data Suppose we have this data Then then then gives gives gives Since the OR is greater than 1, there is a positive association between exposure/treatment and the outcome. Since the OR is greater than 1, there is a positive associati... Since the OR is greater than 1, there is a positive association between exposure/treatment and the outcome.This suggests the exposure or treatment may increase the odds of the outcome. Excel example data Usman Zafar Paracha 2 Usman Zafar Paracha Usman Zafar Paracha Excel example odds ratio Excel example odds ratio outcome B2 shows exposure and outcome,.1003 B2 shows exposure and outcome, C2 shows exposure and no outcome B2 shows exposure and outcome,C2 shows exposure and no outcome Absolute Risk in the Treatment Group Absolute Risk in the Treatment Group Absolute Risk in the Treatment Group =B2/(B2+C2) =B2/(B2+C2) =B2/(B2+C2) syntax.1006 syntax syntax Probability of an event (e.g., side effect or disease) occurring in the treatment group. Probability of an event (e.g., side effect or disease) occurr... Probability of an event (e.g., side effect or disease) occurring in the treatment group.Used to measure the incidence in the group receiving the intervention. illustration.1008 Usman Zafar Paracha 1.1009 Usman Zafar Paracha Usman Zafar Paracha example.1010 example example Suppose we have this data.1011 Suppose we have this data Suppose we have this data Then.1012 then then gives.1013 gives gives In the treatment group, 20% of individuals experienced the event (e.g., disease, side effect, or outcome being studied). In the treatment group, 20% of individuals experienced the ev... In the treatment group, 20% of individuals experienced the event (e.g., disease, side effect, or outcome being studied).This is a relatively high risk or chance, depending on the context. Excel example data.222 Usman Zafar Paracha 2.1015 Usman Zafar Paracha Usman Zafar Paracha Break Excel example for absolute risk Excel example absolute risk outcome B3 shows non-exposure and outcome, B3 shows non-exposure and outcome, C3 shows no exposure and n... B3 shows non-exposure and outcome,C3 shows no exposure and no outcome Absolute Risk in the Control Group Absolute Risk in the Control Group Absolute Risk in the Control Group =B3/(B3+C3) =B3/(B3+C3) =B3/(B3+C3) syntax.1021 syntax syntax Probability of an event occurring in the control group. Probability of an event occurring in the control group. Estab... Probability of an event occurring in the control group.Establishes the baseline risk without treatment. illustration.1023 Usman Zafar Paracha 1.1024 Usman Zafar Paracha Usman Zafar Paracha example.1025 example example Suppose we have this data.1026 Suppose we have this data Suppose we have this data Then.1027 then then gives.1028 gives gives In the control group, 10% of individuals experienced the event without the treatment. In the control group, 10% of individuals experienced the even... In the control group, 10% of individuals experienced the event without the treatment.This represents the baseline or natural occurrence of the event. Excel example data.227 Usman Zafar Paracha 2.1030 Usman Zafar Paracha Usman Zafar Paracha Break.1031 Excel example absolute risk control Excel example absolute risk control outcome C12 shows Absolute Risk in the Treatment Group, C12 shows Absolute Risk in the Treatment Group, C13 shows Abs... C12 shows Absolute Risk in the Treatment Group,C13 shows Absolute Risk in the Control Group Relative Risk (RR) Relative Risk (RR) Relative Risk (RR) =C12/C13 =C12/C13 =C12/C13 syntax.1036 syntax syntax Ratio of risk in the treatment group to the control group. Ratio of risk in the treatment group to the control group. Me... Ratio of risk in the treatment group to the control group.Measures how much more (or less) likely an event is under treatment. illustration.1038 Usman Zafar Paracha 1.1039 Usman Zafar Paracha Usman Zafar Paracha example.1040 example example Suppose we have this data.1041 Suppose we have this data Suppose we have this data Then.1042 then then gives.1043 gives gives The risk or chance in the treatment group is twice as high as the risk in the control group. The risk or chance in the treatment group is twice as high as... The risk or chance in the treatment group is twice as high as the risk in the control group. Excel example data.232 Usman Zafar Paracha 2.1045 Usman Zafar Paracha Usman Zafar Paracha Break.1046 Excel example relative risk Excel example relative risk outcome C12 shows Absolute Risk in the Treatment Group,.1049 C12 shows Absolute Risk in the Treatment Group, C13 shows Abs... C12 shows Absolute Risk in the Treatment Group,C13 shows Absolute Risk in the Control Group Absolute Risk Increase (ARI) Absolute Risk Increase (ARI) Absolute Risk Increase (ARI) =C12-C13 =C12-C13 =C12-C13 syntax.1052 syntax syntax Difference in risk between treatment and control group, when risk is higher in treatment group. Difference in risk between treatment and control group, when ... Difference in risk between treatment and control group, when risk is higher in treatment group.Used when treatment increases risk (e.g., side effects) or chance. illustration.1054 Usman Zafar Paracha 1.1055 Usman Zafar Paracha Usman Zafar Paracha example.1056 example example Suppose we have this data.1057 Suppose we have this data Suppose we have this data Then.1058 then then gives.1059 gives gives The treatment increases the absolute risk of the event by 10 percentage points compared to the control group. The treatment increases the absolute risk of the event by 10 ... The treatment increases the absolute risk of the event by 10 percentage points compared to the control group.This means for every 100 people treated, 10 more will experience the adverse event due to the treatment. Excel example data.237 Usman Zafar Paracha 2.1061 Usman Zafar Paracha Usman Zafar Paracha Break 5 Excel example absolute risk 2 Excel example absolute risk 1 Excel example absolute risk outcome.242 C18 shows Number Needed to Harm (NNH) C18 shows Number Needed to Harm (NNH) C18 shows Number Needed to Harm (NNH) Number Needed to Harm (NNH) Number Needed to Harm (NNH) Number Needed to Harm (NNH) =1/C18 =1/C18 =1/C18 syntax.1066 syntax syntax Number of patients needed to be treated for one to be harmed. Number of patients needed to be treated for one to be harmed.... Number of patients needed to be treated for one to be harmed.Smaller NNH implies more harmful treatment. illustration.1068 Usman Zafar Paracha 1.1069 Usman Zafar Paracha Usman Zafar Paracha example.1070 example example Suppose we have this data.1071 Suppose we have this data Suppose we have this data Then.1072 then then gives.1073 gives gives For every 10 people treated, 1 person will be harmed due to the treatment (i.e., they would not have experienced the event if they hadn't received the treatment). For every 10 people treated, 1 person will be harmed due to t... For every 10 people treated, 1 person will be harmed due to the treatment (i.e., they would not have experienced the event if they hadn't received the treatment).A low NNH (like 10) indicates that harm occurs relatively frequently due to the treatment. Excel example data.243 Usman Zafar Paracha 2.1075 Usman Zafar Paracha Usman Zafar Paracha Break 6 Excel example number needed Excel example number needed outcome C14 shows Relative Risk (RR) C14 shows Relative Risk (RR) C14 shows Relative Risk (RR) Odds Ratio.1079 Relative Risk Increase Relative Risk Increase =C14-1 =C14-1 =C14-1 syntax.1081 syntax syntax Proportional increase in risk due to treatment. Proportional increase in risk due to treatment. Used when tre... Proportional increase in risk due to treatment.Used when treatment increases adverse events. illustration.1083 Usman Zafar Paracha 1.1084 Usman Zafar Paracha Usman Zafar Paracha example.1085 example example Suppose we have this data.1086 Suppose we have this data Suppose we have this data Then.1087 then then gives.1088 gives gives The relative increase in risk due to the treatment is 100% (i.e., 1) — i.e., the event is twice as likely in the treatment group as in the control group. The relative increase in risk due to the treatment is 100% (i... The relative increase in risk due to the treatment is 100% (i.e., 1) — i.e., the event is twice as likely in the treatment group as in the control group. Excel example data.249 Usman Zafar Paracha 2.1090 Usman Zafar Paracha Usman Zafar Paracha Break 7 Excel example relative risk increase outcome Excel example relative risk increase Excel example relative risk increase 1 C14 shows Relative Risk (RR).1092 C14 shows Relative Risk (RR) C14 shows Relative Risk (RR) Attributable Fraction among the Exposed (Afe) Attributable Fraction among the Exposed (Afe) Attributable Fraction among the Exposed (Afe) =(C14-1)/C14 =(C14-1)/C14 =(C14-1)/C14 syntax.1095 syntax syntax Proportion of risk among the exposed that is due to the exposure. Proportion of risk among the exposed that is due to the expos... Proportion of risk among the exposed that is due to the exposure.Indicates how much of the risk is due to treatment/exposure. illustration.1097 Usman Zafar Paracha 1.1098 Usman Zafar Paracha Usman Zafar Paracha example.1099 example example Suppose we have this data.1100 Suppose we have this data Suppose we have this data Then.1101 then then gives.1102 gives gives 50% of the risk in the treatment group is attributable directly to the treatment itself. 50% of the risk in the treatment group is attributable direct... 50% of the risk in the treatment group is attributable directly to the treatment itself.In other words, half of the cases in the treated group would not have occurred without the treatment. Excel example data.1104 Usman Zafar Paracha 2.1105 Usman Zafar Paracha Usman Zafar Paracha Break 8 Excel example attributable fraction Excel example attributable fraction exposed Excel example attributable fraction exposed outcome C12 shows Absolute Risk in the Treatment Group,.1112 C12 shows Absolute Risk in the Treatment Group, C13 shows Abs... C12 shows Absolute Risk in the Treatment Group,C13 shows Absolute Risk in the Control Group Odds Ratio.1113 Absolute Risk Reduction (ARR) Absolute Risk Reduction (ARR) =C13-C12 =C13-C12 =C13-C12 syntax.1115 syntax syntax Difference in event rates between control and treatment, when treatment reduces risk. Difference in event rates between control and treatment, when... Difference in event rates between control and treatment, when treatment reduces risk.Measures benefit from treatment. illustration.1117 Usman Zafar Paracha 1.1118 Usman Zafar Paracha Usman Zafar Paracha example.1119 example example Suppose we have this data.1120 Suppose we have this data Suppose we have this data Then.1121 then then gives.1122 gives gives A negative ARR means that the treatment increased the risk by 10 percentage points. A negative ARR means that the treatment increased the risk by... A negative ARR means that the treatment increased the risk by 10 percentage points.In effect, this is actually an Absolute Risk Increase of +0.1.This suggests the treatment is harmful, not protective. Excel example data.1124 Usman Zafar Paracha 2.1125 Usman Zafar Paracha Usman Zafar Paracha Break 9 Excel example absolute risk Excel example absolute risk reduction Excel example absolute risk reduction outcome C23 shows Absolute risk reduction (ARR) C23 shows Absolute risk reduction (ARR) C23 shows Absolute risk reduction (ARR) Number Needed to Treat (NNT) Number Needed to Treat (NNT) Number Needed to Treat (NNT) =1/C23 =1/C23 =1/C23 syntax.1137 syntax syntax Number of patients who need to be treated to prevent one adverse event. Number of patients who need to be treated to prevent one adve... Number of patients who need to be treated to prevent one adverse event. Lower NNT means more effective treatment. illustration.1139 Usman Zafar Paracha 1.1140 Usman Zafar Paracha Usman Zafar Paracha example.1141 example example Suppose we have this data.1142 Suppose we have this data Suppose we have this data Then.1143 then then gives.1144 gives gives A negative NNT is a red flag—it means the treatment harms rather than helps. A negative NNT is a red flag—it means the treatment harms rat... A negative NNT is a red flag—it means the treatment harms rather than helps.In this case, it aligns with the Number Needed to Harm (NNH):Every 10 people treated, 1 person is harmed instead of helped. Excel example data.1146 Usman Zafar Paracha 2.1147 Usman Zafar Paracha Usman Zafar Paracha Break 10 Excel example number treated Excel example number treated outcome C14 shows Relative Risk (RR).1154 C14 shows Relative Risk (RR) C14 shows Relative Risk (RR) Relative Risk Reduction Relative Risk Reduction Relative Risk Reduction =1-C14 =1-C14 =1-C14 syntax.1157 syntax syntax Proportional reduction in risk due to treatment. Proportional reduction in risk due to treatment. Reflects tre... Proportional reduction in risk due to treatment.Reflects treatment efficacy relative to baseline. illustration.1159 Usman Zafar Paracha 1.1160 Usman Zafar Paracha Usman Zafar Paracha example.1161 example example Suppose we have this data.1162 Suppose we have this data Suppose we have this data Then.1163 then then gives.1164 gives gives A Relative Risk Reduction (RRR) of −100% (i.e., -1) means the treatment doubled the risk instead of reducing it. A Relative Risk Reduction (RRR) of −100% (i.e., -1) means the... A Relative Risk Reduction (RRR) of −100% (i.e., -1) means the treatment doubled the risk instead of reducing it.Normally, RRR is positive when treatment reduces risk.A negative RRR shows that the treatment increased the relative risk. Excel example data.1166 Usman Zafar Paracha 2.1167 Usman Zafar Paracha Usman Zafar Paracha Break 11 Excel example relative risk reduction 1 Excel example relative risk reduction 2 Excel example relative risk reduction outcome C14 shows Relative Risk (RR).1174 C14 shows Relative Risk (RR) C14 shows Relative Risk (RR) Preventable Fraction among the Unexposed (Pfu) Preventable Fraction among the Unexposed (Pfu) Preventable Fraction among the Unexposed (Pfu) =1-C14.1176 =1-C14 =1-C14 syntax.1177 syntax syntax Proportion of events in the unexposed group that could have been prevented with exposure (treatment). Proportion of events in the unexposed group that could have b... Proportion of events in the unexposed group that could have been prevented with exposure (treatment).Relevant when treatment is protective. illustration.1179 Usman Zafar Paracha 1.1180 Usman Zafar Paracha Usman Zafar Paracha example.1181 example example Suppose we have this data.1182 Suppose we have this data Suppose we have this data Then.1183 then then gives.1184 gives gives This metric is usually used to show how much disease could be prevented in the unexposed group if they had been exposed (treated). This metric is usually used to show how much disease could be... This metric is usually used to show how much disease could be prevented in the unexposed group if they had been exposed (treated).A value of −1 implies that none of the events were preventable with treatment—in fact, all were caused by the treatment. Excel example data.1186 Usman Zafar Paracha 2.1187 Usman Zafar Paracha Usman Zafar Paracha Break 12 Excel example preventable fraction Excel example preventable fraction 2 Excel example preventable fraction outcome B2 shows exposure and outcome,.1195 B2 shows exposure and outcome, C2 shows exposure and no outco... B2 shows exposure and outcome,C2 shows exposure and no outcome, Odds in Treatment Group Odds in Treatment Group Odds in Treatment Group =B2/C2 =B2/C2 =B2/C2 syntax.1198 syntax syntax Ratio of events to non-events in the treatment group. Ratio of events to non-events in the treatment group. Used to... Ratio of events to non-events in the treatment group.Used to calculate odds ratios. illustration.1200 Usman Zafar Paracha 1.1201 Usman Zafar Paracha Usman Zafar Paracha example.1202 example example Suppose we have this data.1203 Suppose we have this data Suppose we have this data Then.1204 then then gives.1205 gives gives The odds of the event occurring in the treatment group are 1 to 4 (since 0.25 = 1/4). The odds of the event occurring in the treatment group are 1 ... The odds of the event occurring in the treatment group are 1 to 4 (since 0.25 = 1/4).This means for every 1 person who experiences the event, 4 do not. Excel example data.1207 Usman Zafar Paracha 2.1208 Usman Zafar Paracha Usman Zafar Paracha Break 13 Excel example odds treatment Excel example odds treatment outcome B3 shows non-exposure and outcome,.1216 B3 shows non-exposure and outcome, C3 shows no exposure and n... B3 shows non-exposure and outcome,C3 shows no exposure and no outcome Odds in Control Group Odds in Control Group Odds in Control Group =B3/C3 =B3/C3 =B3/C3 syntax.1219 syntax syntax Ratio of events to non-events in the control group. Ratio of events to non-events in the control group. Baseline ... Ratio of events to non-events in the control group.Baseline odds of event. illustration.1221 Usman Zafar Paracha 1.1222 Usman Zafar Paracha Usman Zafar Paracha example.1223 example example Suppose we have this data.1224 Suppose we have this data Suppose we have this data Then.1225 then then gives.1226 gives gives The odds of the event in the control group are 1 to 9 (i.e., for every 1 person who experiences the event, 9 do not). The odds of the event in the control group are 1 to 9 (i.e., ... The odds of the event in the control group are 1 to 9 (i.e., for every 1 person who experiences the event, 9 do not). Excel example data.1228 Usman Zafar Paracha 2.1229 Usman Zafar Paracha Usman Zafar Paracha Break 14 Excel example odds control Excel example odds control outcome
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