Network Analysis of the Multidimensional Symptom Experience of Oncology

Abstract

Oncology patients undergoing cancer treatment experience an average of fifteen unrelieved symptoms that are highly variable in both their severity and distress. Recent advances in Network Analysis (NA) provide a novel approach to gain insights into the complex nature of co-occurring symptoms and symptom clusters and identify core symptoms. We present findings from the first study that used NA to examine the relationships among 38 common symptoms in a large sample of oncology patients undergoing chemotherapy. Using two different models of Pairwise Markov Random Fields (PMRF), we examined the nature and structure of interactions for three different dimensions of patients' symptom experience (i.e., occurrence, severity, distress). Findings from this study provide the first direct evidence that the connections between and among symptoms differ depending on the symptom dimension used to create the network. Based on an evaluation of the centrality indices, nausea appears to be a structurally important node in all three networks. Our findings can be used to guide the development of symptom management interventions based on the identification of core symptoms and symptom clusters within a network.

Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

A Pairwise Markov Random Field (PMRF) or an undirected graphical model with 6 nodes, A to F. The presence of edges between nodes indicates the conditional dependency between them.

Figure 2

The estimated networks of 38 cancer symptoms across the “occurrence” dimension (a) without the identified communities and (b) with the identified communities (walktrap algorithm). Nodes represent symptoms and edges represent pairwise dependencies between the symptoms, after controlling for all of the other correlations of a given node. The 38 cancer symptoms represented in the nodes above are coded in the following fashion: difcon: Difficulty Concentrating, pain: Pain, energy: Lack of Energy, cough: Cough, nervous: Feeling Nervous, hotflash: Hot Flashes, drymouth: Dry Mouth, nausea: Nausea, drowsy: Feeling Drowsy, numb: Numbness or Tingling in Hands or Feet, chest: Chest Tightness, difbreath: Difficulty Breathing, difsleep: Difficulty Sleeping, bloat: Feeling Bloated, urinate: Problems with Urination, vomit: Vomitting, sob: Shortness of Breath, diarrhea: Diarrhea, sad: Feeling Sad, sweats: Sweats, sexual: Problems with Sexual Interest or Activity, worry: Worrying, itch: Itching, appetite: Lack of Appetite, abdominal: Abdominal Cramps, increaseapp: Increased Appetite, wtgain: Weight Gain, dizzy: Dizziness, swallow: Difficulty Swallowing, irritable: Feeling Irritable, mouthsore: Mouth Sore, wtloss: Weight Loss, hairloss: Hair Loss, constipat: Constipation, swelling: Swelling, taste: Change in the Way Food Tastes, myself: I Do Not Look Like Myself, skin: Changes in Skin.

Figure 3

The estimated networks of 38 cancer symptoms across the “severity” dimension (a) without the identified communities and (b) with the identified communities (walktrap algorithm). Nodes represent symptoms and edges represent a partial correlation between the symptoms, after controlling for all of the other correlations of a given node. The 38 cancer symptoms represented in the nodes above are coded in the following fashion: difcon: Difficulty Concentrating, pain: Pain, energy: Lack of Energy, cough: Cough, nervous: Feeling Nervous, hotflash: Hot Flashes, drymouth: Dry Mouth, nausea: Nausea, drowsy: Feeling Drowsy, numb: Numbness or Tingling in Hands or Feet, chest: Chest Tightness, difbreath: Difficulty Breathing, difsleep: Difficulty Sleeping, bloat: Feeling Bloated, urinate: Problems with Urination, vomit: Vomitting, sob: Shortness of Breath, diarrhea: Diarrhea, sad: Feeling Sad, sweats: Sweats, sexual: Problems with Sexual Interest or Activity, worry: Worrying, itch: Itching, appetite: Lack of Appetite, abdominal: Abdominal Cramps, increaseapp: Increased Appetite, wtgain: Weight Gain, dizzy: Dizziness, swallow: Difficulty Swallowing, irritable: Feeling Irritable, mouthsore: Mouth Sore, wtloss: Weight Loss, hairloss: Hair Loss, constipat: Constipation, swelling: Swelling, taste: Change in the Way Food Tastes, myself: I Do Not Look Like Myself, skin: Changes in Skin.

Figure 4

The estimated networks of 38 cancer symptoms across the “distress” dimension (a) without the identified communities and (b) with the identified communities (walktrap algorithm). Nodes represent symptoms and edges represent a partial correlation between the symptoms, after controlling for all of the other correlations of a given node. The 38 cancer symptoms represented in the nodes above are coded in the following fashion: difcon: Difficulty Concentrating, pain: Pain, energy: Lack of Energy, cough: Cough, nervous: Feeling Nervous, hotflash: Hot Flashes, drymouth: Dry Mouth, nausea: Nausea, drowsy: Feeling Drowsy, numb: Numbness or Tingling in Hands or Feet, chest: Chest Tightness, difbreath: Difficulty Breathing, difsleep: Difficulty Sleeping, bloat: Feeling Bloated, urinate: Problems with Urination, vomit: Vomitting, sob: Shortness of Breath, diarrhea: Diarrhea, sad: Feeling Sad, sweats: Sweats, sexual: Problems with Sexual Interest or Activity, worry: Worrying, itch: Itching, appetite: Lack of Appetite, abdominal: Abdominal Cramps, increaseapp: Increased Appetite, wtgain: Weight Gain, dizzy: Dizziness, swallow: Difficulty Swallowing, irritable: Feeling Irritable, mouthsore: Mouth Sore, wtloss: Weight Loss, hairloss: Hair Loss, constipat: Constipation, swelling: Swelling, taste: Change in the Way Food Tastes, myself: I Do Not Look Like Myself, skin: Changes in Skin.

Figure 5

Centrality indices for the estimated network of 38 cancer symptoms shown in Figs 2a to 4a.